eric17422001

Have not been here in a long time!

I have been working on a problem with my wife's '91 RS 3.1 car.

When the engine is at operating temp and idling all by itself or when you take your foot off the gas to coast to a traffic light, the engine will shutoff. Sometimes it occours while you are in a turn and you suddenly loose your power steering. Thus my wife is not touching this car until I get this worked out.

The car has a zillion miles on it, always starts up instantly even if it has not been driven in weeks. The distributor is an Auto Zone reman with less than 10,000 miles on it. Has Mallory spiral core wires, AC plugs, recent fuel filter. Cannot find any external vacuum leaks when using propane or carb spray. The battery to block ground is good and solid, the positive cable is new from battery to starter for another issue I had. (car not cranking when hot intermittently) Fuel pressure the last time I checked was 42 psi at idle.

I thought this was an idle air control problem, I have done the de carbon to the IAC passage in the throttle body several times, cleaned the pintle of the idle air control, and gone through the factory service manual's "Idle Learn" proceedure several times. I finally replaced the IAC with a new one.

Car runs great otherwise, strong acceleration for what it is, I could go down the highway at 70mph all day without a hiccup. But drive it around town, and under 1500 or 1600 RPM, it sputters and misses. Idle is rich.

A year or so ago, I borrowed an Auto X ray from someone that has since moved away, and datalogged it at idle. The "BLMs" as they are called were at 160, max rich, but the O2 sensor readings were telling it it was lean, so I replaced the O2 sensor with a GM Delco. No real change.

I have NO CODES. I have no way currently to datalog this thing and find out what it is doing when it stalls.

I will also ad that I have replaced the brake booster as it was leaking internal vacuum and I thought that was the problem.

I had someone suggest "It's the EGR!" so I tried unplugging it and driving around- no change. BUT, it does not set the Check Engine light due to it being unplugged, is that right?

Any ideas? I am stumped and frustrated!

dontellmymom

i had this problem then i changed my 02 sensor it went away i tried a "new" egr valve first and it did nothing

mvftw

iTrader: (1)

Try the Distributor Module...

KrisW

iTrader: (5)

Also test the ignition coil. These cars really cook the coils due to the mounting point.

jstrdn90rs

Sounds like a vacuum leak to me ,and I need to ask you if you checked the charcoal canister purge valve?..its a solenoid operated by the ECM .basically it opens/closes it during throttle positions and certian conditions.IF its stuck open you will get a large vacuum leak,and when you apply the brake during a stop or turn it creates even more of a vacuum leak from the booster ..engine can't overcome the leaks and shuts off?.good luck

eric17422001

Well I decided to put the car in the garage and start by doing some much needed maintanence.

The timing chain had never been touched to my knowledge, so I went in to it- that thing had about 3/8" of play in it and the sprockets were very worn. So a new chain and gear set (SA Gear) went in, and a new water pump while I was at it. The car has developed an oil leak at the front of the engine, and while I was scraping the goo off the front of the block above the timing cover a bead of silicone came out.....the bead at the front of the intake manifold!

Well then it was time to pull the manifold. Since I had to pull the fuel rail and injectors, I mailed them to www.cruzinperformance.com to have them sonic cleaned and tested. However, I emailed the guy then sent the injectors and got a reply from him to the effect that unlike the last injectors he did for me (I used to have an '88 Iroc Z with the TPI 305) the V6 injectors were from what he called the first generation of GM "multec" injectors, and they have a high failure rate. The misfiring at low RPM's and sooty idle out the pipe he said were clear signs this was happening. I will have him test them anyway to prove if they were bad.

While it's apart, I have a set of Comp 1.6 stamped roller tip rockers I got in a pile of V6 parts I got off a guy years ago, I will put them on. May add two whole horsepower to the squirrel cage. Man that six is tiny with all the front accessories stripped off of it along with the top end.

I will reseal everything, fresh injectors, go through the timing, go over all the block grounds and body to block grounds, put it back together with that new AC compressor and reciever/dryer I have had since last summer sitting on my workbench.

Do I have aspirations of making a street screamer out of this? Not since I got ripped of of a grand for a "turbo Kit" by former moderator of this board and author of one of the stickies at the top of this board (do I sound bitter??)

But I hope to have this thing back running reliably as a second car so my wife who really owns it does not want to get rid of it!

jstrdn90rs

Sorry to hear your bitterness..I do know that feeling well,so I can relate.I also did my timing chain and I even checked it before entering after it.The dampner makes it appear like its still good,since my waterpump was leaking I decided to go after it anyway.Once the dampner came off,you could tell how much slop was in it.The new chain will make a big difference along with the injectors.Mine was like a whole new car..night and day difference.One thing I am tossing around at the moment is only for the 90-92 v6 owners.Its a fan switch coming on at 200.The current fan switch is grounded from the ECM and we have the area in the pass.head for the switch ..so why not run a Jet or Hypertech switch for the older models and run a toggle switch and tap into the ECM-fan relay wire?.SO in turn you would have both 200 and 220 fan operation at the switch of a button??.I have been told it wouldnt work ,and it would.I think it would just adding another ground to the circuit.?What do you think?Keep that camaro on the road..

eric17422001

I recall I put a Grand National fan switch in my LB9, it makes the primary fan come on at 180 I think. Of course we have only one fan. Lightens the car for speed!

jstrdn90rs

You would have to run a 160 or find a 170 t-stat to make the Grand national switch work?.the aftermarkets make a 185 and a 176 fan switch.If I recall...otherwise the fan would come on as soon as the t-stat opened if you ran both 185 switch and 180 t-stat.I dont see any problems running this..it shouldnt hurt the ECM.Its just a ground ..not like its a power supply line.I have t-tops on mine and while I got them off at a stop light, when the weather is 80 degrees I dont like the temp going up to 220..although it never gets to that point.But what would happen in traffic or getting around an traffic accident?.thats the theory behind this idea.Turning the AC on with tops off is stupid just to cool down the motor.In the winter you can switch over to the ECM ground and fan kicks on at 220?probably never get that hot during the winter..and if one fails at least you have the other as back-up?

86TpiTransAm

This is true. I too have a 91 3.1 in my Firebird and am currently in the process of replacing my injectors due to failure. My injector failure caused the ECM not to send ground to make the injectors work.

In the process of finding out what to get for replacements I was pointed to Linder Tech (www.lindertech.com). They have a list of the top 12 injectors with high failure rate and the Multec injectors that came in these 3.1s are #1 on the list with the highest failure rate. Linder Tech sells exclusive reconditioned Bosch DRI injectors with a LIFETIME warranty that are a direct replacement for the Multecs. They're just $199.99 plus $10 shipping and they're quick. I ordered mine Monday morning, he sent them UPS ground, and I had them on Wednesday. It's probably worth it to mention that they do everything that Cruzin Performance does and then some. I had my LT1 injectors off my 86 TA reconditioned at Cruzin. They do good work as well but Linder is just as good if not better.

CamaroKingpin

or it could be the fuel filter. got a 92 3.1 did the same thing, changed it. hasnt cut off since. its a cheap change.

eric17422001

OK so I finally got it all back together and it's running pretty good now, idles like a watch at 700 RPM, NO black soot out the pipe when I stomp it from a dead stop. Not stalling when you take your foot off the gas either.

Things I found- timing chain was very sloppy, oil and likely vacuum leaks from the intake manifold base, the terminals on the distributor cap were very corroded and so was the pickup inside. Cleaned up the distributor, resealed intakes, put on 1.6 rockers.

It still has a problem I have not gotten into yet- it pulls strong up to about 4 grand then seems to labor from 4-5 grand every two out of three times you stomp on it and try to let it wind thru the gears. If you let off the gas slightly, say 7/8ths throttle instead of full, it pulls better. Fuel pressure is steady at 42psi while this is going on. Possible TPS problem? Until I get an ALDL cable for my laptop and use turnerpro to datalog the thing I won't know.

I can't say specifically what was wrong, but I suspect vacuum leaks and some really bad injectors had something to do with it!

Interestingly I have "known" this car since it had about 170,000 on the clock, and it always had a mid level knock when hot. I thought it to be a wrist pin slap, but now it's GONE. Car has 207,000 on it and that's with the speedo working erractically for the last couple years (another issue) so I think it was timing chain slap making the noise, that's all I can figure.