1989 5.0 Will not go in to closed loop, bogs when accelerated, no codes

[Dadpool]

Nice work!
Sounds like you are well on your way
Cheers

We got it back to the mechanics and now they are saying it is going in to closed loop from monitoring the O2 Sensor, but that it is now running too lean! Ugh! They are pointing at the injectors, but have tapped out. They can't find ones that they can say will without a shadow of a doubt, will work. We brought it home and I did some research and ordered in 8 Standard motor FJ712 after seeing it listed on multiple sites for a proper fit and flow rate. It will start and idle smooth as can be, and if you barely touch the gas pedal it will go, but as soon as you try to accelerate it feels like, well for a lack of better terms, something is holding it back, worse than before. Other than setting the timing back to 10 degs they didn't do anything else other than check to make sure it is going in to closed loop. I tried to set the timing back with the vacuum gauge and it would barely idle. TPS, MAP and IAC have all been re-replaced. The IAC did help, but not much. My son drove it last night after replacing and clearing memory and he said it ran great, until he shut it off at the gas station to put fuel in it, then on the way home it was back to poo. Maybe it's time to try that other distributor... IDK. There are no KOEO codes and the only code I got with a KOER was a Knock sensor, which it does have and I haven't changed it, but from what I found that shouldn't cause this kind of issue. There are 0 vacuum leaks, I bypassed the EGR with no improvement, and fuel pressure is steady and not losing pressure after 30+ minutes of being off. Any other ideas are appreciated.

 

[Tiha]

Kind of starting to wonder if the PCM is bad. Also having the timing off, or ******** because of the knock sensor I sure think could do that.

 

[Dadpool]

Kind of starting to wonder if the PCM is bad. Also having the timing off, or ******** because of the knock sensor I sure think could do that.

PCM had been replaced 3 times by the mechanics that had it, and it never solved the running rich issue, but I do understand that doesn't mean it's not causing this issue.
For the Knock sensor, looks like Amazon, Ebay are the options for replacements since no local parts store even has a listing for it. What would happen if it was unplugged for testing purposes only to see if that helped?

 

[L\Bronco]

PCM had been replaced 3 times by the mechanics that had it, and it never solved the running rich issue, but I do understand that doesn't mean it's not causing this issue.
For the Knock sensor, looks like Amazon, Ebay are the options for replacements since no local parts store even has a listing for it. What would happen if it was unplugged for testing purposes only to see if that helped?

Hey Dadpool, (sorry for the silence, been focussed on my mustang project)
Im struggling with the “mechanics” assessment.
If you did a koer test and the only code you have is the 25 for the knock sensor. Then is not running lean. (One of the koer tests is O2 resonse. Push it rich, pull it lean and check that the O2 sensor reading follows.)
Unless its lean during the bogging/ lack of power.
You verified fuel pressure, but, did you measure while the symptom was happening?
Tape the fuel press gauge to the windshield and watch it while it is accelerating with no power.
If you got a 25 for the knock sensor KOER, but no KOEO knock sensor code, then the sensor is probably ok.
The koer code just means it didn't ping during the “dynamic response” portion of the Koer test. (When the code 10 happens, you are supposed to goose the theottle briefly to WOT and off. It should ping as the timing is pegged at max advance.)
I dont feel the knock sensor is an issue

 

[Dadpool]

Hey Dadpool, (sorry for the silence, been focussed on my mustang project)
Im struggling with the “mechanics” assessment.
If you did a koer test and the only code you have is the 25 for the knock sensor. Then is not running lean. (One of the koer tests is O2 resonse. Push it rich, pull it lean and check that the O2 sensor reading follows.)
Unless its lean during the bogging/ lack of power.
You verified fuel pressure, but, did you measure while the symptom was happening?
Tape the fuel press gauge to the windshield and watch it while it is accelerating with no power.
If you got a 25 for the knock sensor KOER, but no KOEO knock sensor code, then the sensor is probably ok.
The koer code just means it didn't ping during the “dynamic response” portion of the Koer test. (When the code 10 happens, you are supposed to goose the theottle briefly to WOT and off. It should ping as the timing is pegged at max advance.)
I dont feel the knock sensor is an issue

No worries on the delay. I understand. I have been working on my 79 Cherokee getting it ready for a camping and wheeling trip. My son was hoping to take his Bronco, but it doesn't look like it's going to be up to par by Fathers day weekend.
Testing the fuel pressure while the symptom is happening, it does not change at all. It's at 30 at an idle and 30 when driving and it bogging down.
Also, pulling the vacuum line to the FPR while at idle makes the pressure jump up to 40.

 

[L\Bronco]

No worries on the delay. I understand. I have been working on my 79 Cherokee getting it ready for a camping and wheeling trip. My son was hoping to take his Bronco, but it doesn't look like it's going to be up to par by Fathers day weekend.
Testing the fuel pressure while the symptom is happening, it does not change at all. It's at 30 at an idle and 30 when driving and it bogging down.
Also, pulling the vacuum line to the FPR while at idle makes the pressure jump up to 40.

Ok cool, fuel press is right on point!
Did you say it was normal for your son after a reset then back to no power after a reset?
And does WOT act any different than heavy accell?(say…3/4 throttle)
Sorry for all the questions, its acting weird so I want as much data as I can get before any more suggestions.
Cheers

 

[Dadpool]

Ok cool, fuel press is right on point!
Did you say it was normal for your son after a reset then back to no power after a reset?
And does WOT act any different than heavy accell?(say…3/4 throttle)
Sorry for all the questions, its acting weird so I want as much data as I can get before any more suggestions.
Cheers

For grins and giggles, we warrantied the IAC, Cleared codes and then he said it was good up until he shut it off.
WOT It struggles to get up to speed, still bogging down. I'll mention that I did get a NAPA TPS sensor today and put it on to verify that I had a good part. No change.
I did a smoke test for grins, probably not the best type, but I put smoke in the break booster line with the intake ports blocked off and I am seeing smoke come out of the TPS sensor area. Could this be causing un-metered air to get in and cause the issue?

 

[L\Bronco]

For grins and giggles, we warrantied the IAC, Cleared codes and then he said it was good up until he shut it off.
WOT It struggles to get up to speed, still bogging down. I'll mention that I did get a NAPA TPS sensor today and put it on to verify that I had a good part. No change.
I did a smoke test for grins, probably not the best type, but I put smoke in the break booster line with the intake ports blocked off and I am seeing smoke come out of the TPS sensor area. Could this be causing un-metered air to get in and cause the issue?

Unlikely, leakage around the throttle shaft is unavoidable.
Your issue is not likely a vacuum leak.
At WOT pressure in the manifold equals atmospheric pressure, so leaks have little to no effect.
Yours is improperly measured air or improperly metered fuel.
A start would be, check the vacuum line to the map sensor, Sometimes they delaminate internally and delay the change in vacuum data so the truck goes lean intermittently and usually on hard accell.
For fuel, the only concern would be injector flowrate. (You have certainly verified pump volume and pressure)
Based on your symptoms, I wouldnt start there as it would act up consistently.
Another option could be that its not the engine at all. If the one way clutch on the stator in the torque converter seizes it will feel like the brakes are coming on the faster you try to go.
If that oneway freewheels, it will be an absolute dog off the line, but will start to normalize approaching hwy speed and up.
Lots to consider.
Hope that helps
Cheers!

 

[Dadpool]

Unlikely, leakage around the throttle shaft is unavoidable.
Your issue is not likely a vacuum leak.
At WOT pressure in the manifold equals atmospheric pressure, so leaks have little to no effect.
Yours is improperly measured air or improperly metered fuel.
A start would be, check the vacuum line to the map sensor, Sometimes they delaminate internally and delay the change in vacuum data so the truck goes lean intermittently and usually on hard accell.
For fuel, the only concern would be injector flowrate. (You have certainly verified pump volume and pressure)
Based on your symptoms, I wouldnt start there as it would act up consistently.
Another option could be that its not the engine at all. If the one way clutch on the stator in the torque converter seizes it will feel like the brakes are coming on the faster you try to go.
If that oneway freewheels, it will be an absolute dog off the line, but will start to normalize approaching hwy speed and up.
Lots to consider.
Hope that helps
Cheers!

Here is an update after a couple of months.
It's been to 2 transmission shops, the first one I didn't really trust, but my son took it there anyway. The second one had the same verdict. It's not the transmission or torque converter.
The second shop is willing to try and diagnose the remaining issue, but once again, it is not being an easy task. They have had it about an month and a half and the most they have found it that moving the timing higher than it should be does improve the issue, but it doesn't cure it. Before taking it down to shop 2, I put the original distributor back in to see if the problem stayed the same, and it did, so I would cross off the distributor and TFI module as the issue. I did notice, that the distributor is a major pain in the tail to get dropped in. It starts off fine, but then it gets hung up on the last inch or so an you have to mess with it for a while and then it magically drops. I'm not sure if it is getting hung up on the oil pump rod or the cam, but something hangs it up badly. I then took that same distributor in put it in my Falcon that I dropped an 88 Crown Vic 302 in, and it dropped perfectly, so the distributor isn't the issue. I think I will give them the rest of August and then pull it back from their shop, get it back home and pull apart the timing components and take another look. If it's timing, its gotta be something in that area, and hopefully not the cam.

 

[L\Bronco]

Your dist was getting hung up on the oil pump drive. Its a hex drive so you might need to turn the crank a bit and turn it back after the dist drops.
Sometimes a few tries will nudge the pump into alignment.

It's at 30 at an idle and 30 when driving and it bogging down.
Also, pulling the vacuum line to the FPR while at idle makes the pressure jump up to 40.

Sorry Dadpool, I missed this the first time. The fuel press should go up and down with load. Your fuel press rises when you pull the vac line, but not when the load is there.
Check the vac line that goes to the press reg. (I think it tees off to the map sensor) If so, check/replace the line between the tee and the manifold fitting. (There shouldn’t be any valves or controls in this line.) It should have a direct connection to manifold vacuum at all times. It may be delaminated internally or someone may have incorrectly installed a vacuum check valve (VCV) in there.
Hope that helps!
Good luck
Cheers

 

[Dadpool]

Your dist was getting hung up on the oil pump drive. Its a hex drive so you might need to turn the crank a bit and turn it back after the dist drops.
Sometimes a few tries will nudge the pump into alignment.


Sorry Dadpool, I missed this the first time. The fuel press should go up and down with load. Your fuel press rises when you pull the vac line, but not when the load is there.
Check the vac line that goes to the press reg. (I think it tees off to the map sensor) If so, check/replace the line between the tee and the manifold fitting. (There shouldn’t be any valves or controls in this line.) It should have a direct connection to manifold vacuum at all times. It may be delaminated internally or someone may have incorrectly installed a vacuum check valve (VCV) in there.
Hope that helps!
Good luck
Cheers

All Vacuum lines go direct to the tree on the upper intake, and have all been replaced with rubber ones. I know those are not the best option, because they can collapse under vacuum, but all of the plastic lines were cracking and breaking when touched. No check valves were put on during replacement. I appreciate your follow up. As I mentioned, another shop has it at the moment, so I'm unable to do any further testing for a while.

 

[L\Bronco]

Rubber is fine, it takes many years for them to break down.
Thanks for the reply, Ill pause the diag till you get her back.
Just strange that the press red is retaining vacuum somehow.
(no load sense matches your symptom though)
Possibly a leaking check valve at the brake booster…Ill stop now.
Cheers

 

[johnnyreb]

Greetings fellow Bronco owners.

I have a 1989 with the 5.0 AOD that my son and I have been fighting for about 3 years after putting in a new engine. I won't go through all the details but will list the most recent that we are running in to.I

I gave up after a couple of years and sent it to 2 different mechanics. The first one back burnered it because it was taking too much time to diagnose.
I took it to another recommend one and they found a bad ECT, replaced but it was still running rich. After checking seveal other item they replaced the ECM and it started running correctly and not rich. They sent it home with us and my son drove it for a month and it started running rich again. We took it back in december and they relooked over everything and came up with the injectors we got were wrong causing it to not go in to closed loop. They were a set of reman ones from AutoZone. I know they are not known for reliable parts but its what we could afford. After double, tripple checking their site, in store I wasn't convenced that the injectors were the issue, but I got the manager to warranty them and got another set of the same type for them to try. It still was running rich and not going in to closed loop. They back burnnered it. I suggested that they try a set of know good injectors I had out of an 88 302 from a Crown Vic that I put in my Falcon. They agreed, so I pulled them and gave them to the mechanic. A month later they still haven't tried them, so I brought it home and put them in.Other than a couple of broken O rings they went in with no issues, and I did replace the O rings.
It started and seemed to be doing ok, but still rich and not going in to closed loop.

I since replaced the ECT again ( I had a spare new one for my Falcon) still no change. I attempted to test the sensor but giving the location, it is difficult to get a reading once at temp. I tried with it running under hot water and it seems to be within specs, I don't remember the values off hand. I decided to run a new line to the ECM for the ECT, keeping the original wires in the loop since I seen it provides grounds to the TPS, MAP and several others.
Now as of this weekend with a cleared ECM it will start, it calibrates a bit after reaching temp then tries to go in to closed loop, but then jumps back in to closed loop, bumping the idle to 1000 rpm. When trying to drive it, it bogs down at low RPMs, but smooths out at around 2500 to 3000. Once it is shut off, it is hard to start again.

To the best I can tell by spraying some carb cleaner on it (before it warms up) there are no vacuum leaks in any vacuum lines, which have all been replaced from the plastic lines. No leaks on the TB and between the upper and lower intake.

Fuel pressure when KOEO is around 30ish and holds steady, so I don't believe the the injectors are leaking. Fuel pressure seems good when running, but there is no change in how it runs if the vacuum line is removed from the FPR. Research found maybe a weak or back fuel pump. The one on the frame is making noise, but with a auto stethoscope to the tank, I can not hear it buzz when key is turned on.

Timing is at 10 btdc with spout unplugged and advances to around 20 at idle.
Parts replaced that could be causing the issues, and slightly inconclusive test results
TPS, IAC, ECT Multiple times, MAP, ACT, FPR during the install of the engine. It does have a knock that was not replaced.

I have reverted back to the stock wiring for the ECT, verified all ground and pin outs from sensor connectors via continuity, and that they are all getting the 5v ref power.

This does have the emissions removed, so we get a TAD and TAB code, but that is expected. Otherwise, just 11, system pass.

I will be verifiying the in tank pump again and getting that replaced this weekend, if NAPA will order in the pump before I bring them the old one to warranty.

Plugs and plug wires, cap and rotor are new. Reman Dizzy, so TFI module or PIP could be suspect but not likely.

Any other ideas I can try on this thing?

Alot of the NEW PART you buy--are junk when you leave the store. Most is made in CHINA. Your better off going to a junk yard and buying a used part. Anyone who has worked on vehicles--will tell you that---don,t waste your time or money on CHINA JUNK---THEY DO MAKE PARTS IN AMERICA--TYPE IN AUTO PARTS MADE IN AMERICA AND HIT ENTER. Good luck.

 

[johnnyreb]

Here is the update from this last weekend and this week.

Both fuel pumps have been replaced. It wasn't getting adequate pressure on the fuel rail while running down the road. Being the easiest, and with a warranty, I replaced the on the fame one first. This helped but it was still not good enough. Tested pressure from the intank, and got nothing. I'm not sure how it was running at that point with no pressure from the tank, but it was. Dropped the tank and replaced. It is under warranty, but NAPA was gonna take 3 days to get it so did an O'Rileys that was in stock and will warranty the NAPA one for when it goes out.
This made quite the improvement, but still sluggish on acceleration, and getting a code 35. After the pump replacements, I noticed that the vacuum gage was showing the timing was too early. I know, that should be more for older engines with a vacuum advance vs EFI, but figured what the ****, lets try it. I set the timing based on the guage getting it as close to the green as it could and having it run smooth. Checking with a light, it's at around 20 deg BTDC. Plugged the spout back in, unplugged the IAC and set the idle to run at 550-600 then plugged it back in. Let the memory clear on the computer and we again we had improvement. Doing more research I found that the EVS should be plugged in to the throttle body and not the tree directly(?) otherwise it is getting constant vacuum and could cause the EVS to pull vacuum on the EGR. Switched it to the top port on the throttle body. This seemed to help yet a little more, but still not fully. Next the Cat was removed and patched. This has made yet another improvement. Normal acceleration feels great, but hard acceleration still feels like something is holding it back and we have a CM Code 33. I have verified that the EGR is free and clean, even replaced just as a precaution. EVP is getting proper voltage, and signal looked good, but that was Saturday, and I don't remember the exact values it was getting. I think if we can solve this CM 33 code, we will be good. Seems no matter what the EGR is opening a little when it shouldn't be, causing it to feel held back. I do plan on getting it to TDC and checking to make sure I have the distributure stabbed right or if I missed a tooth, but that will likely be next weekend when weather looks to be warmer. I also have my 79 Cherokee coming back from the shop tommorrow and need the garage to get a heater working in it since the weather decided we're back in winter after a few weeks of 60's & 70's.

You say you replaced BOTH FUEL PUMPS? If the are AIR TEX---THAT IS PROBABLY YOUR PROBLEM. AIRTEX IS JUNK. I WENT THROUGH 5--Then I bought CARTER and have not had any problems.

 

[Dadpool]

Alot of the NEW PART you buy--are junk when you leave the store. Most is made in CHINA. Your better off going to a junk yard and buying a used part. Anyone who has worked on vehicles--will tell you that---don,t waste your time or money on CHINA JUNK---THEY DO MAKE PARTS IN AMERICA--TYPE IN AUTO PARTS MADE IN AMERICA AND HIT ENTER. Good luck.

Thanks for the information. I did already know that the parts you get from the local auto parts stores are China junk. I can't say that I am willing to go buy something like an Engine Coolant Temp sensor from a salvage yard though. I have the same 50/50 chance if it would work, and a 100% chance of not being able to exchange it or return it for a refund.
The only problem with getting American made parts, is you have to order them. When you take a long weekend to work on something like this, it's a PIA when you get 30 mins into it and then parts are a week out. So I get what I can get.

 

[Dadpool]

You say you replaced BOTH FUEL PUMPS? If the are AIR TEX---THAT IS PROBABLY YOUR PROBLEM. AIRTEX IS JUNK. I WENT THROUGH 5--Then I bought CARTER and have not had any problems.

Both were NAPA Echlin line of products at first. Now the in tank is whatever O'reillys had in stock, because again, long weekend, warranty parts were days out, and I already had the tank dropped.

 

[johnnyreb]

Both were NAPA Echlin line of products at first. Now the in tank is whatever O'reillys had in stock, because again, long weekend, warranty parts were days out, and I already had the tank dropped.

Have you check the COMPLET GAS LINE.? fROM the tank all the way to the fuel pump and from the fuel pump to the carbeurator? Also check to see if the line is the SAME SIZE TUBEING. Someone had DIFFERENT SIZE TUBEING on mine and caused me problems. Make sue all the tubeing is the SAME SIZE..

 

[Dadpool]

Have you check the COMPLET GAS LINE.? fROM the tank all the way to the fuel pump and from the fuel pump to the carbeurator? Also check to see if the line is the SAME SIZE TUBEING. Someone had DIFFERENT SIZE TUBEING on mine and caused me problems. Make sue all the tubeing is the SAME SIZE..

It has is all factory lines.

 

[L\Bronco]

Hey Dadpool!
Get it home yet?

 

[Dadpool]

Hey Dadpool!
Get it home yet?

Not yet. I stopped by to get an update last week, and they are still leaning towards timing related. I'll give them a bit more time and see what they find if anything.