'88 rough idle when hot....burnt smell

[Guest imported_Flash]

1988 Reatta

Hesitating at speed when warmed up (>120 degrees) and idling rough when stopped after warm up. Runs good (normal) when cold (106 degrees). Over the last 3 days it has degraded, culminating yesterday afternoon with a burnt smell inside the cabin but not the engine compartment. Start off from stop seems like a slipping tranny or a engine timing problem. At speed, seems like the trans is trying to find a gear.

Per the FSM, I believe it is a bad PCV with a tune up or bad gas as the next items to tackle. Possible Catalytic converter, ICA, ECM etc.

Given the smell inside the cabin and the description of problem, what are the thoughts here?

Catalytic converter replaced 11-2-99

Trans service 6-11-02

Cam sensor/mag replaced 6-22-02

ECM replaced 1-14-03

I'm leaning to the PCV as it has been 2 years on current tune up. But what about the smell?

[Jim]

Dan,

Sometimes when they smell it is from the Catalytic converter getting too hot. Check your codes and see if there is an E044 in the history. That would be a lean Oxygen sensor reading and if the engine runs lean it also runs hot on the exhaust. If you replaced the converter 4 years ago I wouldn't think it would be bad this soon, although if it is bad you would have restricted exhaust, a smell and a bad running engine but if it only runs bad when it goes into closed loop then the converter is probably good.

Jim

P.S. I sent your parts out today via Priority Mail.

[Guest imported_Flash]

Thanks Jim.

I'll tackle the cat if the tuneup/PCV/STP injector cleaner doesn't fix current problem. Several months ago I posted about a noise shortly after start up that sounded like "bees in a can" and a responder suggested the cat converter then. So maybe it just gave out. I'll post after Saturday morning's tuneup.

PS....sure hope the sockets fix the lighting item...sounds like I do not want the dimmer job.

[Guest EDBS0]

My experience is that the only thing that STP cleans out is your wallet. Many will argue that today's gas is all that you need. NOT! The BMW guys highly recommend that you use Red-Line SI-1 Injector and Valve Detergent Treats 100 Gallons per bottle. I used to purchase it here at $3.83 each when purchasing a case of 12, appears to be higher now.

The burnt smell???

Have you ever taken your air intake hose off and cleaned the throttle plate. Clean both front and back with a rag soaked with a spray degreaser or throttle body cleaner. IAC is usual culprit for rough idle.

Season's best to you and Cheryl

Found a deal for you here.

[Guest imported_Flash]

Robert,

Thanks for the heads up. I'll try the Red Line. Season's Best as well.

[BuickCollector]

3 comments:

I don't know if you replaced the cat with an OEM or aftermarket, but working for a company which manufacturer's cats, I can tell you the aftermarket requirements are a lot less than OEM (ie. not as much precious metal, therefore they don't last as long). Ever wonder why GM cat's can cost $300 and up and aftermarket's are around $100?

Also, try GM's TOP Engine Cleaner to clean out your throttle body. I use it regularly especially on my GNs. It completely eliminates pre-detonation (pinging).

When I had a burning smell (under the hood) along with a rough idle, it turned out to be the ignition module frying itself.

Good Luck.

[Guest imported_Flash]

Daryl,

Thank you for your thoughts. The replacement cc was likely done at a muffler type service shop, so probably is not OEM.

I'll have some answers tomorrow morning when I take it in for winter prep service.

[Guest Greg Ross]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Also, try GM's TOP Engine Cleaner to clean out your throttle body. I use it regularly especially on my GNs. It completely eliminates pre-detonation (pinging).

</div></div>

Is this as in "Knock Counts" problems?

[BuickCollector]

Yes. Engine knock as recorded as Knock Counts.

After running 2/3 of a can at 1800rpm through the TB (air intake path), then dumping the last 1/3 can in the engine and letting it stall, waiting a few minutes and restarting...all knock is gone AND the engine runs smoother.

DON'T WAIT TOO LONG, IT WILL FOUL PLUGS!

FOLLOW THE INSTRUCTIONS ON THE CAN.

It is avail. as liquid (pour-in) or aerosol. Chrysler calls their version Combustion Chamber Cleaner.

I know Reattas don't have the same sensitivity to knock as GNs, but this stuff just plain works on any car.

The more white smoke it generates while performing the procedure, the most gunk its cleaning out.

Smooth sailing when done!

[Guest Greg Ross]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> I know Reattas don't have the same sensitivity to knock as GNs </div></div>

Except perhaps the Turbo and S/C versions, that is!

What do you run for spark plug gap in the GNs'?

[BuickCollector]

AC Delco CR43TS 35 gap

Note the C for "Commercial" - thicker electrode, most resistant to damage from detonation.

R44TS 35 gap, is the stock config., I believe.

Then again, 14psi is stock for '86/'87s, where I run 18-20 on 93.

[cpu]

Hi guys,

I run CR43TS on my 1984 T-Type with similar gap.

I've been meaning on getting the Top Engine Cleaner. Is it generally available at a local dealer parts counter?

If you know the GM part number, I may just buy it from one of the online GM parts guys with my next order.

[BuickCollector]

Part # 1050002 ???

This is what is on other websites.

Don't have a can handy.

Also, here's a good how-to article.

http://www.gnttype.org/techarea/maintenance/cleaner.html

Remember this stuff goes in the AIR intake path.

It is NOT fuel inj. cleaner which goes in the tank.

I've never seen it anywhere but GM parts dealers (and Chrysler I've been told).

[Guest imported_Flash]

Had the tune up done this am and changed the PCV. Still running rough (missing). Tune up guys wanted to change the coil and new wires (300 bucks) but I declined. Missing worse after tune up, so dropped it off at the dealer. Just called, diagnosed it as the ignition module($430installed). Checking the FSM, the ignition module controls things below 400 rpm where the ECM takes over after that. The missing occurrs after warm up and at 750-800 rpm. The ECM is under warranty for another 2 weeks.

Any thoughts?

[Guest imported_Flash]

Latest call from dealership.....not the ignition module. New module had the exact same missing cylinders as the replaced unit and actually running worse. Putting original module back in. Will not get back to diagnosis until Monday. I suggested they look at ECM.

[Roadster90]

Flash,

Dealer diagnosis is a fair bet, but get the ICM at Advance or Auto Zone....can't remember but probably 60 - 75.00 .... fairly easy to replace .... ECM is probable as well. Called the act of or process of elimination ... might want to check the search function for insight ... good luck!

[Guest imported_Flash]

Thanks all for the help and reply's....culprit in this case was the Crank Sensor. (trying to post a picture but don't seem to have the know how).

Price for the CS was 48.00. We won't discuss the fees assessed for the diagnosis. Apparently the Crank Sensor is a link between the ignition module and the ECM. ECM tested OK. Car running fine now. No explanation for the burnt smell in the cabin and not in the engine compartment. If the CS got fried, then I would think I would smell it in the engine bay, but that was not the case.

Brief recap.....car ran good cold, bad after 120+ on temp. Idled rough like it wanted to stall but did not. Hesitated on accelleration from stop, but did not stall. Engine seemed OK at speed, but sometimes would seem to be searching for a gear. These were the symptoms that were diagnosed to be the result of a bad Crank Sensor. Hope this helps someone else down the road.

I'll try to post a photo of the sensor when I get it figured out. I think I've got some instructions from EDBSO somewhere. Found the "image" tab but don't know the URL. Got it!!!

Attachment attached.

[padgett]

First time I've heard of a crank sensor doing something other than failing completely. Rough over 120F coolant sounds like when it goes into closed loop and really first time I've heard of a CS doing that.

Well good that they found it.

[Don B.]

Check your coil pack. If the nuts on the bottom aren't

tight, could cause what you described.