Idle Problem

Outside temp display bright/dim could (well, most likely is) the HVAC control unit itslef. There were a number in which that happened, IIRC the fix is to disassemble it and re-solder the connections. I think there was a post about that fix somewhere but I can't find it.

Albertj

But Albert... does that fix address the idle and slamming into reverse when cold issues?

Hard4unot2 wrote:

But Albert... does that fix address the idle and slamming into reverse when cold issues?

No, he's just warning you away from a probable red herring, because these ECC heads are NOTORIOUS for display problems...

WOW! I had a "work van" but it died last Friday so now I have to drive the Riv everyday... quite frankly, it's the first time I drove it more than two days in a row since I bought it. I'm all in now though so I'll do what I have to do to get it right.

Hard4unot2 wrote:

Thanks Addict - will the emissions related problem likely effect the cold weather starting?

Just to clarify, the Diagnostic Trouble Codes (DTC's) cover virtually every electronic system in the engine & transmission, as well as gas tank, ABS, Trac Control, Airbags, etc... The government is only concerned with problems that cause pollution, but in the real world the MIL/SES/Check Engine lights are set to tell you that there is something that the computer sees out of whack, whether it is "an emissions component" or not. A bad cam sensor reading might mean unburned hydrocarbons to the EPA, but to the rest of us it's a repair problem...

Happy New Week, Guys! So I had to give my neighbor a Jump Saturday morning and I saw the Belt Tensioner doing a dance, making the noise I previously described and I touched it and it felt as if something was loose inside. I took it to a shop but of course the engine was warm by then and it had stopped the dancing and the Maycanik said a little dance was normal anyway. To me the loss of power to the Gauges indicates it just may be the Belt Tensioner that may be causing my messed up cold start idling... what you guys think? Also, is the installation of the Belt Tensioner as easy as it looks?

HEY GUYS.... Am I getting warm with the Belt Tensioner? Please don't abandon me now!

You could have a weak tensioner, but try this - remove the belt and try wobbling all of your idler pullies. Odds are one or two of them is getting... loose.

Hard4unot2 wrote:

HEY GUYS.... Am I getting warm with the Belt Tensioner? Please don't abandon me now!

Your issue, Herb, is the tensioner dancing is a symptom not a problem.

What you can do is get a wrench of the proper size (one tensioner takes a Torx T-30 bit and the other takes I think a 15 or 17MM hex socket) and take the belts off the tensioners. The idlers are attached with *reverse threaded* bolts. That is, if you turn them as if you were loosening a normal bolt, that will oppose the tensioner spring and allow you to slip the belt off. (By the way that is also the direction to turn to tighten the bots. To replace the idler and tensioner pullies you have to turn the bold as if you were tightening a normal bolt. The bolts will be TIGHT and the tolerances are close so you basically can slip replacement pullies on there and you'' be good to go if that's your problem) Umm... back to the diagnosis... then all you have to do is turn the pullies by hand to figure out what's up. Any binding or scraping and wha-la, you have found a bad or problem component.

Do not be surprised to find more than one problem - that is, don't be surprised to find an idler pulley bearing and the alternator binding, or someother component. No way for me to tell sitting here.

If you use a torque wrench to move the tensioner you can figure out if its spring has weakened, however I do not know the spec - maybe someone else does and can post it. I imagine it's 30 or 40 lbs minimum but I really don't know. Tensioners weaken over time but it takes a real long time.

I'll stop here by saying that this is all easier than it looks, you'll notice that once you try it.

Albertj

Had the '95sc Scanned and the fault came up EGR but the fix was the MAT Sensor... Service Engine Light went out and the Idle is great... might I still have a Trojan lurking to strike?

Who did the fix and what did they do? If a dealer or someone experienced with the GM 3800 engine did the work, they may well have cleaned the EGR (they can be cleaned instead of replaced and usually work fine after a good cleaning) and found the sensor was flaky when comparing the sensor's readings with standards. Instead of having you come back, they replaced the sensor (most likely it was the MAP - Manifold Absolute Pressure - sensor. I do not know what a MAT sensor is).

Please tell us more.

Albertj

Manifold Air Temperature sensor. It sits right up top on the right - a 2" square chip looking piece. Before he started the work he said the EGR could be cleaned but in the final analysis it was the MAT not the EGR.

Thank you for correcting me.

Albertj

Hard4unot2 wrote:

Manifold Air Temperature sensor. It sits right up top on the right - a 2" square chip looking piece.

Personally I think it was the MAF - Mass Air Flow - sensor...

There was a part called a MAT sensor, it's the same thing as an IAT sensor, but it was screwed into the intake manifold, thus the name. According to RockAuto, though, the VIN-1 '95 used the same IAT as my '97...

Now, I could believe that the nomenclature in the manuals and the computer might still have referred to IAT as MAT in '95, however I never saw a square one. The top of the MAF sensor on the other hand, is a rectangular piece, mounted up on top on the right as you look at the engine. As Albert mentioned, the MAP sensor is also rectangular, though I don't know where it is mounted on a '95...