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Buick Reatta runing rough


rben
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I ditched the old Mass some time ago, looks like a trip to the yard in my future.

As for the pressure regulator, it is not leaking. i did a pressure check several months ago and had a 40ish pressure then.

The ECM was replaced, does PROM data transfer or is it pre-installed in a new one?

Mileage, 116055 not a whole lot.

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An update, changed out the MAS and fuel pressure regulator. runs good at idle mostly. Found a pattern to the issue. It appears to start running like it is missing when in overdrive, RPMs less then 1800, and you give it just enough gas to speed up. Does something change when doing overdrive? it does not appear to do it in other gears. Speed might be part of the equation as well.

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Low RPM/moderate load miss is a typical secondary ignition issue - coils/plugs/plug wires particularly where they go under the alternator. Have you tried watching the engine idle in the dark to see if any arcing ?

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Not sure if this is the same as mine but I had issues with mine for years stalling, rough idle, no start, etc. and my mechanic changed out virtually every part imaginable.  Turns out it was a vacuum leak at the throttle body I  believe it was.

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no,  i haven't watched it in the dark. it does do the "miss fire" all the time-ish. just more noticeable at low idle and high gear.I shall test out the cables next. i suspect the vacuum too. i know 2 points in vacuum that are good. only a few more to check out.

Edited by rben (see edit history)
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Did some testing with the vacuum. When disconnected or plugged off there is a change in how it runs but only for moment then the system adjusts and it is back to "normal". The miss fire acts like my other car with the cap and rotor did till i cleaned up the cap. Being this is electronic control, that cant be done.

This would tell me the running issue is more mechanical or electronic feedback related.

So, what controls the timing in a low RPM/Idle state? I had the ECM replaced, could there be a programming issue? Or is my cam or crank sensor not quite right? 

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1 hour ago, rben said:

The miss fire acts like my other car with the cap and rotor did till i cleaned up the cap.

 

If you haven't installed new plug wires and spark plugs do it.  Don't just assume they are good.  A miss that occurs at low RPM under high load conditions, like accelerating up a hill in high gear with the converter locked up at low RPM,  is almost always caused by the secondary ignition system.  The ICM, coils, spark plug wires and plugs should all be suspect with spark plug wires being #1.  Something as simple as a hairline crack in the porcelain on a spark plug, or even carbon tracking on the porcelain, can cause a miss under load as you describe.  (Been there, done that) You shouldn't move on to other things until you know for certain that all of the secondary ignition parts are in excellent condition, especially the spark plug wires.

 

While you have the spark plugs out check the compression.  A burnt valve can cause a miss at idle and sometimes under load depending on how bad it is. If you have a valve burnt bad enough to cause a miss under load you should notice a difference in the way the engine idles.

 

The timing is adjusted electronically and can't be adjusted manually.

 

You can unplug the cam sensor and you probably won't tell a difference other than the SES light coming on setting a code E041 and maybe a small loss of MPG. The cam sensor just optimizes the timing of the fuel injectors opening (not spark). It's not going to cause a miss under load as you describe.

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On 2/25/2020 at 4:25 AM, DAVES89 said:

I believe 63viking came up with a replacement. maybe he will respond with an answer.

Hey Daves89, 

I purchased my first Reatta June 3, 2020.  It's a polo green 91 with 144k and desperate TLC needs.  Living in th Fox River valley means I must run two license plates.  I noticed in another post that you addressed to his issue.  Would you know where I could lay my hands on a front license bracket?

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  • 4 weeks later...

Well the car is running bad in the loaded state. Replaced the pugs and wires. ran rough for short time with 2 wires in the wrong place but it ran. Straightened that out, but now...

it runs with misses with the MAF unplugged but has no issues in final drive gear. with MAF plugged in and final drive it does the spasm thing at low RPMS. So who knows how the ECM controls the system? it seems the data from the MAF is not right or the ECM is not using the data as needed. I figure it must be running close loop with the sensor unplugged. I am running out of... trying to find the cause of its issue. i am almost to the point of selling to highest bidder.

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I admire your dedication to this problem child. I am assuming the check engine light isn't on and no error codes turn up? Daves89 recently had a strange issue with erratic operation due to a front brake dragging which placed an abnormal load on the engine which seemed to indicate an engine problem. Sometimes the seemingly unrelated can cause secondary symptoms. If you suspect a sensor acting up, try watching the readout in diagnostics while driving, especially when and where it is prone to having an issue. For instance, watch the MAF signal. I usually see 4-6grams/sec at warm idle and a  relatively stable increase as engine speed and load increases. Similar for TPS, should be around .4v at warm idle and smooth increase as throttle is opened. This can be done with the key on and engine off just to make it easier. What does the ignition timing look like, stable at idle around 20deg at warm idle maybe increasing a couple degrees when dropped in gear? It is highly variable when underway so hard to make a suggestion on that. What do the fueling parameters look like, the Integrator and Block Learn? Target for both items is 128 and may go above or below that as it adjusts but shouldn't stay locked at a single reading, such as 150 or 128. How about O2 cross counts while driving and up to temperature. What is intake air temperature reading? Shouldn't be too far off of the outside air temperature displayed in the climate control, at least while underway, except one may be in *F and the other *C so convert. Do you get a knock signal or especially knock retard indication while driving?

Essentially the ECM needs reasonable and logical data to calculate what to do. If the data is corrupt, maybe outside the expected range, but still within the system limits, it might not show a code, but will cause trouble. That's why we disconnect sensors to revert to open loop and base programming to see if it stabilizes or improves.

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  • 3 weeks later...

I decided to check in to the cam interrupter, saw it was ..odd. I took a tool to probe the magnet and it stuck to the tool. Then i tried to put it back in...didn't work as planed.  So now i replaced the timing change and gears, put in a new interrupter and plan to put it all back together. So here is a question, what is the recommended sealant to use for the cover?

Oh, and the chain dampener is really worn.

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52 minutes ago, rben said:

I decided to check in to the cam interrupter, saw it was ..odd. I took a tool to probe the magnet and it stuck to the tool. Then i tried to put it back in...didn't work as planed.  So now i replaced the timing change and gears, put in a new interrupter and plan to put it all back together. So here is a question, what is the recommended sealant to use for the cover?

Oh, and the chain dampener is really worn.

The cover doesn't get a specific sealant, it should get a new gasket, most of which have sealing beading as part of their assembly. If you have a photo of the worn tensioner I would be very interested.

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4 hours ago, rben said:

Thanks for the nice photos. That is an original and it lasted how many miles? Looks like 150k miles or so. Almost impossible to find an original style replacement, and I am sure you will find the new style with a long shoe type design which gives the illusion that there is more contact area which there isn't. I can't find a photo of the new style at the moment except one totally worn away.

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24 minutes ago, Dashmaster said:

That  Chain Tensioner looks like the small 88 part that was changed in 89.  The one listed above is the later design. I made this change on my 88 when I did the chain.

If this is in a 91, That makes me wonder how it got in here ?

I am not sure when that changeover occurred? Every engine I have torn down, '88 thru '90, all LN3 engines, has had the small tensioner block like that original. I have not opened up the front of a Series I L27 Tuned Port engine, which first appeared in the '90 Buick Regal, so not sure if it is a model year or perhaps engine model change??

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New timing chain, gears, tension-er and cam sensor. It runs, but still has that strange hiccup thing in the fourth gear and only in that gear. So i am wondering if anybody has wiring diagram. I had the ECM replaced, long story, and i wounder if that has something to do with it. At the same time when i try to manually run the 1# cooling fan, It does not work. I found  however it does run when fan 2 is on high.

With a diagram i my find a wiring issue, i found a few on line but i trust someone here might have better version.

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Would help if youput the year/model in your .sig but "shock connected to the motor on the passenger side." means it is not an '88 and no resistor so the cooling fan circuit is found in section 8A-31 of the factory service manual.

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It is a 89, and has a fan front driver side, engine side and 1 passenger side, on the out side. The out side one might be for the AC unit. Meanwhile any thought about the ECM and the over drive gear link?  I wounder because before the ECM was replaced it did not do the hiccup thing. The shop i took it to, because it died along the road and would not start, replaced the ECM because they said that was why it would not start. So i question if the data that was traversed was all good or all there.

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Is this a shudder that occurs right around 50mph under steady throttle or light acceleration? The most common reason is a spark misfire under low rpm and high load right about where fourth gear and the TCC engages. The other reason in that speed range is the clutch in the converter is not locking up cleanly. 

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I had a bad issue with shudder/ miss under load. I went over things several times and after a lot of time swapping parts to test. I found the large wire harness that runs left to right on the firewall was hanging down near OX sensor and plug wires. I pulled it back up and wire tied it. Problem was finally solved. You can lookup my posts on this to see everything I tried to solve this issue.

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I always had the OX sensor wire routed away from everything before the move. I am not sure which source was inducting into the other.  This issue kept the car from making the Allentown show. I was at such a loss on the issue I put the car up for

sale. I had no idea's left. Then took one more look over everything. Thought the harness was low, tied it up and took for test drive. Problem solved. Been running great since. 

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9 minutes ago, Dashmaster said:

I always had the OX sensor wire routed away from everything before the move. I am not sure which source was inducting into the other.  This issue kept the car from making the Allentown show. I was at such a loss on the issue I put the car up for

sale. I had no idea's left. Then took one more look over everything. Thought the harness was low, tied it up and took for test drive. Problem solved. Been running great since. 

 

No matter what it did, if the problem went away when you tied up the harness you can't argue with the results. Glad you got it fixed.

Edited by Ronnie (see edit history)
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1 hour ago, Dashmaster said:

I always had the OX sensor wire routed away from everything before the move. I am not sure which source was inducting into the other.  This issue kept the car from making the Allentown show. I was at such a loss on the issue I put the car up for

sale. I had no idea's left. Then took one more look over everything. Thought the harness was low, tied it up and took for test drive. Problem solved. Been running great since. 

I think you had posted about that discovery once before and it is a great find for sure. Greatly appreciate the reminder. I rarely think about that harness as the '90, which is my regular victim, doesn't have the harness in that location. 

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I zip tied the harness up to the engine a while ago while searching for a solution. i will go over it again just to be sure.

It is a bit of a shutter at the 50mph at 4th gear when you give it gas. If you give enough gas and it drops back to third it is fine.

As for the PROM i am not sure i have been trying everything else before taking on the the ECM. I don't have the tools or the equipment to download or verify the data on the ECM is right. This issue has to be data related somehow. As i mentioned it doesn't do the shutter thing with the MAF unplugged.  That tells me the ECM is running a preset program and not using the incoming data with the MAF unplugged. I thought is was the MAF but i have three of them and they all do the same thing.

So as for the clutch, other than it running funny would it have other side effects?

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1 hour ago, rben said:

It is a bit of a shutter at the 50mph at 4th gear when you give it gas. If you give enough gas and it drops back to third it is fine.

As for the PROM i am not sure i have been trying everything else before taking on the the ECM. I don't have the tools or the equipment to download or verify the data on the ECM is right. This issue has to be data related somehow. As i mentioned it doesn't do the shutter thing with the MAF unplugged.  That tells me the ECM is running a preset program and not using the incoming data with the MAF unplugged. I thought is was the MAF but i have three of them and they all do the same thing.

 

The shutter may not be ECM or data related at all. When you unplug the MAF I think it prevents the ECM from going into closed loop. That will keep the torque converter from locking up resulting in less load on the engine when you try to accelerate. A shutter or stumble when trying to accelerate at low RPM with the converter locked up in high gear can be traced back to a weak ignition system a lot of times.  A bad plug wire or spark plug is the primary cause. Don't get caught up in the high tech stuff and overlook the basics.

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Here is an odd question. The ECM has 3 plugs,  2 black and one is orange or red? i got an ECM from a local yard and it was suppose to be the right one (PN:1228253). That was the part number i found searching for a replacement.  The one in the car currently is PN:1228786, which is listed as being for the Cadillac Seville. So what model is suppose to be in the car?

The 1228253 unit is the orange plug, the 1228786 is a red plug. My car has a red plug.

Was there a ECM change?  Meanwhile i am not sure how the PN starting with 16 link to the PN 122.

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What MEMCAL is in it ? (ED99)

 

There were several different computers used in different years. Delco changed its numbering from 12xxx in the 80s to 16xxx in the 90s. Most factory replacements are 16xxx. I am not aware of any that had a red connector

4ecms.jpg

 

Looks like this one but not sure which model lines. Does everything work correctly ?

 

s-l1600.jpg

 

I show ANDP as this but that is a Seville with 4.5 V8

BCC   Year Release Date Eprom ECM Prom ID Scan ID Platform Engine Disp. Trans Trans Type
ANDP   1989 33185 16123760 1227333 3844 3776   EB LR6 4.5  

MAN

 

Curiouser and curiouser..

Edited by padgett (see edit history)
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