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Running rich. Misfire persists...


Alchemy333

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As a heads up to this ongoing issue with this 90 reatta that sat since 2008. 103k mi. These are the steps taken to remedy the situation thus far. Manifold gasket, plugs, wires, coil pack, timing chain, harmonic balancer, crank sensor, cam magnet and sensor, cleaned intake/throttle body components, seafoam top end, PCV, injectors, fuel filter, O2 sensor, all new gaskets, and now the FPR. Fuel preassure now holds around 34lbs at idle, 38lbs max when reved and 40 unplugged. Running the obd1 reader shows fluctuation between rich lean fuel trims... ecm running closed.

 

Took it for emissions pretest to my guy... says its running rich. It has an intermittent misfire at idle and stopped at a light in drive. Fluctuates with an inconsistant vibration every few seconds dropping rpm slightly. In park, @ 2500rpm, I notice a slight variant in rpm... runs smooth otherwise.

 

Every repair/has improved the overall quality of running conditions... but no solution yet. I did order the only emissions purge valve/vent solenoid I could find available from ebay part # BWD CP-216.. and a new emissions canister filter... as my only other thought is it could be leaking partway open. No codes present. For those who've been following this project, im running the original ICM, that came with the car, as the replacements wouldn't run at all.

 

If you guys got anymore ideas, I could use a few... thanx!

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1 hour ago, Alchemy333 said:

For those who've been following this project, im running the original ICM, that came with the car, as the replacements wouldn't run at all.

There is a reason for that. Until you determine what that reason is you will probably not be able to solve all the other issues you are having.

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You need to find a complete running coil and icm package, just to borrow for temporary confirmation that the problem doesn't lie there. Another thing to check, and I admit I have lost track, is the vacuum modulator on the transmission. If the vacuum hose has fluid in it, the engine is burning transmission fluid. Fuel pressure should be adequate but it sounds a bit low. It could just be variance in the gauge calibration? I would expect 2-3psi greater pressure. I do not know what the California Prom calibrations are and your gasoline does not have a stellar reputation for its makeup either, so is some instability to be expected?? What are the readings from ED19 and ED20, Fuel Integrator and Block Learn doing in the suspect areas? Have you tried a vacuum gauge connected to the intake? A regular drop in vacuum may indicate a mechanical issue, sticky/leaky valve? I would think a solid 18+" of idle vacuum 

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2 hours ago, 2seater said:

You need to find a complete running coil and icm package, just to borrow for temporary confirmation that the problem doesn't lie there. Another thing to check, and I admit I have lost track, is the vacuum modulator on the transmission. If the vacuum hose has fluid in it, the engine is burning transmission fluid. Fuel pressure should be adequate but it sounds a bit low. It could just be variance in the gauge calibration? I would expect 2-3psi greater pressure. I do not know what the California Prom calibrations are and your gasoline does not have a stellar reputation for its makeup either, so is some instability to be expected?? What are the readings from ED19 and ED20, Fuel Integrator and Block Learn doing in the suspect areas? Have you tried a vacuum gauge connected to the intake? A regular drop in vacuum may indicate a mechanical issue, sticky/leaky valve? I would think a solid 18+" of idle vacuum 

I haven't been able to locate anyone else with such ICM package. My only option in that area right now would be to purchase another reatta. I was proposed, a while back, to see a low mileage, garaged reatta, supposedly in pristine condition. But, no telling if it would be in order (likely to be sitting longer than this one)... plus, it'd be committing to owning another reatta...lol

 

I'll have to purchase a vacuum guage. It seems I'm now in the process of repurchasing all the tools I lost years back. I'll take a look at that transmission preassure line. Im gonna go ahead and post a video (if this site allows for it) of the active readings. Honestly, im faced with a big learning curve here and a bit over my head. Learning alot though. I'm new to San Diego and don't really know anyone in this business. Aside from this forum... it's pretty much YouTube and I getting this done.

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Just to be clear, the coil/icm set can come from any LN3 powered car, Riv's, LeSabres, Pontiac Bonnevilles etc..

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I posted to YouTube 2 videos. Fuel preassure test and diagnostics. Im not sure what to make of the B411 and E47h codes.

 

Fuel preassure readings...

 

Diagnostic readings...

 

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Did your O2 Sensor ever switch to LEAN?  Have you done any checking of it?

 

Jim

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19 minutes ago, Ohjai said:

Did your O2 Sensor ever switch to LEAN?  Have you done any checking of it?

 

Jim

The exhaust output reading fluctuates rich/lean if thats what tou are asking. I think towards the end of the video it shows this. It is a new sensor also.

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I've not made it all the way through the video yet but the first thing that stands out to me is the coolant temp is 200 degrees and the scanner says the engine is still operating in open loop. At 200* it should be in closed loop. Does the scanner ever show that it goes into closed loop?

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7 minutes ago, Ronnie said:

I've not made it all the way through the video yet but the first thing that stands out to me is the coolant temp is 200 degrees and the scanner says the engine is still operating in open loop. At 200* it should be in closed loop. Does the scanner ever show that it goes into closed loop?

It was showing closed loop the first time I checked.

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This is what I saw at the front of the video. Was the video recorded in parts at different times?

 

alchemy.jpeg

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5 minutes ago, Ronnie said:

This is what I saw at the front of the video. Was the video recorded in parts at different times?

 

alchemy.jpeg

No... I checked it a couple days ago and it was closed. It would have been run a bit longer too that day. Not sure of the temp at the time as all these readings are a bit new to me... or what normal looks like even.

 

I could run it to full operating temp and make a new video if that helps. Are you suggesting the temp sensor may be faulty? It is still the one that came with the car.

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1 minute ago, Alchemy333 said:

I could run it to full operating temp and make a new video if that helps.

I think that would be a good idea. When in open loop the ECM is operating on data tables stored in memory. When it goes into closed loop the ECM starts looking at the O2 sensor and  probably other sensors as well to determine the proper fuel mixture. The readings you show in your video aren't the true readings you will see when the engine is in closed. loop. The ECM should be operating in closed loop by 170* under normal conditions. If not there is a problem keeping that from happening. See if you can get it to go into closed loop and post another video of your readings. By the way, you did a good job on the video. Very helpful. that looks like a really good scanner.

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I just ran through it again.  at 3:17 it is closed loop and it is lean.

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Is there a listing of what these readings should be?  A place that I could try and learn from what is going on with the diagnostics?

I just got a TECH 1A with several modules.  I spent the day trying to learn how to use the instrument and what it is telling me.   My short term memory caused me many problems.  I see something, then try to go back to it and can't find it again.  However, I am blessed with being an OLD may, into his four score years.

 

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Nice videos! I wondered the same as others when I watched the O2 in the rich zone, (above 450mv),and the fuel integrator locked at 128. That must have been at idle, and it is not unusual for the O2 to cool off and stop doing its job. When revved up a bit it started to go rich/lean and the integrator floated around 128. It will always read 128 unless in closed loop. That is pretty normal. Idle conditions, especially extended idling, will go rich. I am not certain why that is but it is one way to keep the catalyst in the converter hot. Your numbers, fuel pressure and engine sound are pretty good. Nothing jumps out to me. Even the FSM will tell you that the engine speed must be raised for a period of time to get everything online, even if the engine coolant is hot. Today, faster computers, heated O2 sensors and O2's before and after the cat are normal. Not so 30+ years ago. 

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I watched the running video a couple more times and the engine definitely needs rpm to get the fueling adjustments via the O2 started. Once it was heated up, it continued to remain active even when it dropped back to the idle range. The UART issue is something in the serial communication. Hard to be specific but it seems to go hand in hand with the weird previous behavior. Did I understand that the engine quit at a stop when driving?

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On 6/8/2023 at 9:01 AM, 2seater said:

I watched the running video a couple more times and the engine definitely needs rpm to get the fueling adjustments via the O2 started. Once it was heated up, it continued to remain active even when it dropped back to the idle range. The UART issue is something in the serial communication. Hard to be specific but it seems to go hand in hand with the weird previous behavior. Did I understand that the engine quit at a stop when driving?

It dosnt ever stall out. It has a slight idle drop and vibration intermittently at a stop. When driving either streets or freeway, I really don't experience any adverse effects. Im going to try to upload a new video today demonstrating this with the reader plugged in and operating at temp.

Edited by Alchemy333
Also, providing the proper method of checking trans fluid is running in park, it shows a quart low. Im gonna remedy the situation but don't feel it will change the immediate issue.
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Also, providing the proper method of checking trans fluid is running in park, it shows a quart low. Im gonna remedy the situation but don't feel it will change the immediate issue.

 

Unless the engine is drinking the fluid?

 

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