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1990 coupe w/146K


ptt

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This 1990 Coupe seems to develope a miss and noticeable drop in power after it warms to operating temperature.  And seems to make the transmission hunt for a gear when pedal is depressed.  I would expect a normal down shift.  I have checked my tranny fluid and it was a quart low so I topped it up.  The engine miss that occurs when the car reaches operating temperature is my main concern.  Thoughts appreciated.

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It could be a weak ignition system. Most likely bad spark plug wires. A lot of people have thought they had an erratic shifting transmission when the problem was really caused by the ignition system breaking down at low RPM when the transmission is in high gear, converter locked and the engine is under load.  

 

Another possibility is a bad O2 sensor since it runs good when cold. The O2 sensor only comes into play when the engine temp reaches about 160 degrees and the fuel system goes into closed loop operation.

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If its low on transmission fluid, with no obvious external leaks, the transmission modulator may be leaking internally. The fluid will be sucked into the engine and burnt while the engine is running. Spark plugs could be fouled, could mess up a oxygen sensor readings too.

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  • 2 weeks later...

 

I spoke to soon...its back to missing at idle when it goes into closed loop.  Cold start and it runs well but once it reaches operating temperature it loses power and is missing.  I have a new Oxygen Sensor so I"ll be installing that and reporting results.

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OK...I replaced the Oxygen Sensor.  Started the car anjd idled it to operating temperature.  It started to miss again when it went into closed loop like before.  I tried to get the codes but the cluster is intermittent.  What ever it is is happening when the system is going into closed loop.  Any thoughts appreciated!

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I went through some of your previous posts and see that you were having the same problem with your 1990 Convertible back in 2017. What did you do to rectify that problem? If it is now fixed why don't you try moving some parts back and forth to isolate the problem? Or if the 1988 is running good swap parts from it as the engine components are the same.

 As has been commented on the ignition system on these engines don't throw codes so it is a case of making sure it is either fuel or electrical and then following that path.

 Usually it is the coil pack, ignition module, spark plug wires, oxygen sensor. 

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I always looked at the "milk shake in the radiator" as transmission fluid in the coolant which means transmission fluid in the engine and coolant in the transmission. Very hard on the transmission.

 A Pastor at my Church contacted me about this. I called Kendall who at the time was a Chrysler mechanic, who took a look at it. He said to me that I should find another transmission and radiator. I got both and he had that transmission out of that Chrysler mini van in less then an hour without a lift working on the floor. Install about the same. One of the most amazing things I ever saw him do on a car. He brushed it off saying "I do that 100's of times at work"...

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Theres no evidence of coolant on the oul dipstick and no bubbles in the overflow coolant jug.  The radiator was dripping coolant around where the upper hose clampes to the radiator.  Just started this after I had replaced old sparkplug wires so I hadnt driven the car.  Could I be so lucky to have avoided getting coolznt into the transmission?  Transmission fluid on the dipstick looks normal.  

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  • 3 weeks later...

So far on the Coupe I have replaced the plug wires and checked plug gap A.060, O2 sensor, coils and put in a new radiator.  It still starts very quickly by just tapping the key.  But when it goes to closed loop at operating temperature it develops a miss and noticable power loss.  Something is triggering the miss when it reaches operating temperature.  Ideas appreciated.   

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7 hours ago, ptt said:

Can this issue possibly be EGR related???

Yes.  EGR is to be released only when the engine reaches operating temperatures, as most of us know, and the amount coming in is to be metered.  That's all a person needs to know.  Two things - and I am no Reatta expert but I was a Mazda-Subaru factory trained dealership mechanic from 1998 to 2005 - the amount metered can be too much and cause drivability issues OR it can be clogged and the computer is making airflow and fuel adjustments "thinking" EGR has been released. 

 

Others who know the EGR issues for Reattas can chime in, but for my restoration of my 1988, I am just assuming the EGR Valve and system are worn out and am replacing.   Keep plugging away.  Let us know what you find out.

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11 hours ago, ptt said:

Can this issue possibly be EGR related???

Often an EGR leak causes a rough or hunting idle, not so much a power loss. The system is generally pretty reliable but can get coked up and need cleaning. There should be no EGR at idle or full throttle but in between the flow varies and can be monitored in diagnostics to see if you can see a correlation between EGR commanded flow and engine performance. You can block the EGR completely to test with a thin metal strip under the valve or even a couple layers of metal foil type duct tape or even aluminum foil. You may expect some ping or knock with the EGR eliminated under some conditions. 

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I will be cleaning the EGR and hoping its the problem.  Ive checked the fuel pressure (its #41).  Would a bad temperature sensor be causing the problem?  As to the hard start with the Convertible, I cleaned the IAC hole and pintle.  They were carboned but not real bad.  It seemed to be a little easier to start and reached normal idle fairly well.  Better than previously.  I will post back my results with the EGR cleaning  on the Coupe. 

Edited by ptt (see edit history)
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One of the e026 code tests is an EGR test. Too bad your IPC doesn't work as you could see what codes you have. I still think it is the ignition module under the coils. Humor me by swapping the entire coil pack Ignition Module off another Reatta that is running well.

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Would the ignition module be so consistant in producing the engine miss exactly when the system goes into closed loop?  The engine starts, idles and doesnt miss a beat until it reaches operating temperature.  Then it justs starts in like its only running on 4-5 cylinders.  I started it cold this morning and let it idle until it reached normal temperature and it was like throwing a switch......misses. 

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To see if the ECM going into closed loop is actually causing the problem unplug the oxygen sensor while the engine is cold. That will prevent the ECM from going into closed loop. Then start the engine and and allow it to fully warm up. Let us know if the engine starts to miss when it warms up or continues to run smoothly as long as it stays in open loop. Knowing that information might be helpful in troubleshooting your problem.

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I drove the Red 60 miles to my brothers house with not a lick of an issue. Pulled in his yard and stopped the car and tried to back the car up a low grade, it wouldn't do it. Had to pull forward and get a running start to get it up the low hill to where I wanted to park it. Went to leave about 3 hours later, started right up went a half mile and died, leaving me to call a tow truck to get home. 

 It can any time and at the same time. It's heat and closed loop is a warmed up car...

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Just a comment but when the system goes into closed loop the mixture is leaned out from cold running and the whole ignition system strains. May also feel when going up a mild hill in O/D (about 45 in an 88). Low rpm/high load.

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The miss is obvious at idle only once it warms up and from then forward.  Hills are even more "straining" to get up once the miss starts.  Im going to try and dig out my injector noids to see if the injectors are ok.  The main thing that baffles me is the fact that the engine only misses when car reaches operating temps.  It runs fine upon cold start up with just a touch of the key!  When it gets to the point it reaches operating temperature it like...pow...the miss starts.  Also, I ordered a new ignition module for under the coils.    

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On 8/29/2019 at 7:05 PM, ptt said:

This 1990 Coupe seems to develope a miss and noticeable drop in power after it warms to operating temperature.

 

On 9/16/2019 at 7:52 PM, ptt said:

Cold start and it runs well but once it reaches operating temperature it loses power and is missing.

 

On 9/18/2019 at 10:59 PM, ptt said:

Started the car anjd idled it to operating temperature.  It started to miss again when it went into closed loop like before.

 

On 9/22/2019 at 10:51 PM, ptt said:

Now it also is acting the same as the Coupe...missing/loss of power ay operating temperature.

 

On 10/16/2019 at 10:05 PM, ptt said:

But when it goes to closed loop at operating temperature it develops a miss and noticable power loss. 

 

On 10/17/2019 at 10:10 PM, ptt said:

The engine starts, idles and doesnt miss a beat until it reaches operating temperature. 

 

On 10/18/2019 at 8:15 PM, ptt said:

The miss is obvious at idle only once it warms up and from then forward.

 

I think I'm starting to see a pattern here.  Maybe the problem is related to the engine reaching operating temperature.

Edited by Ronnie (see edit history)
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I agree with Padgett about spark plug gap. The plugs should be gapped at .045 if using the Magnavox [square coils] and .060 if using the Delco [round coils]. 

 You have three Reattas, which one are you working on or is there more then one with this issue?

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7 hours ago, ptt said:

My 1990 fsm shows the sparkplug gap should be .060.  Is this an error

Not an error. It does work if everything is fresh, including the engine, but a little compromise for our older rides.That was the way it was in that era, designed to help fire leaner mixtures but it does increase the strain on the ignition systems. Some other models recommended up to .080". Reducing the gap a bit increases the reliability of the spark. While the Magnavox is a decent ignition, the Delco style has a demonstrably stronger spark energy.

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I think Ive found the reason(s) for my operating temperature miss finally.  I regapped the SPARKPLUGS to .045 from .060 and  the miss was still there at warmup.  I removed the EGR and it was carboned up to the point that the PINTAL movement was affected so I cleaned it so it moved freely.  Again the miss remained.  My new ICM came in the mail so I installed it.  I did notice that the old ICM was really corroded on the bottom as well as on the mounting bracket.  If I recall isnt this where the unit gets its ground?  Once I got the ICM and new COIL installed I started the engine and idled it to operating temperature.  NO MORE MISS!!!!  I dont think  I put anything on engine that actually wouldnt need to be replaced.  Ive had it almost 8 years and only put a crank sensor on it if I recall so this way I got most of it out of the way instead of an on going PITA sensor replacement issue dragging on all winter!  Thankfully DAVES89 got it right....the  ICM.  Thanks to everyone who helped figure this out!  Youre all amazing!!!    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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