Hi, I recently had a host of carb problems. I rebuilt my stock Q-Jet from my '85 IROC with the L69. Now, my check engine light comes on intermittently. The problem is, I don't have an engine scanner, and don't want to pay some guy $70 Cdn to plug one in. I suspect it is the Mixture Celenoid or the TPS. I think I will just change them, and hopefully the engine code will not set again. I plan to go to the autowrecker and pick up a handful of these sensors. Here are my questions: What Mixture Control Seleniods and Throttle Position Sensors can go on that car? I know that the MC is color coded (there are both black ones and blue ones that I have seen), and I suspect that the TPS is also (I have only seen white ones though). My MC has a blue plastic top and the TPS has a white one. Can I get any MC and TPS that color from any Computer Controlled Q-Jet of the similar era? There are also part numbers on both the MC and the TPS. However, the rebuilt Q-Jet I have and the stock one have different part numbers. Incase I have to be more specific than colors, does anyone know what part numbers will work in my carb? One other question. It is possible that I dont have the mixture set perfect; this is my first real attempt at carb work. If the knock sensor is activated, will the check engine light come on? I could here it pinging the first time I set it up, but now that I have reset it, I can no longer here it. So, incase you got tired of reading, and skipped to end, here are my three questions: 1. If I get the same color of TPS and MC, will they function the same in my car? 2. Does anyone know the part numbers of each selenoid that will work in my car? 3. Does the knock sensor trip the check engine light? Sorry for my long winded post. I tend to be quite verbose Thanks so much, I really appreciatte the input all you knowledgeable people have. [This message has been edited by Draug (edited July 19, 2001).]

You don't need a $30 code reader (although you're paying for the book more than the reader), and you don't have to pay anybody to get the stored codes.

Go to http://www.thirdgen.org/newdesign/faq/thirdgen.shtml on this board, almost at the bottom of the page it tells how to get your trouble codes with a paper clip, and what they mean.

Do that before you hit the used parts dealer. Besides, I doubt they would be very happy about you tearing into their carbs to get those parts.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

five7kid,

I too saw that section of the FAQ. However, I only have 4 connectors, not twelve. My connectors are in the location of connectors 3,4,5,6 in the diagram in that article. I have no idea what to do with that.

Any further suggestions?

By the way, I was not going to just tear apart carbs and leave them without paying for the carb. Even with paying for the carbs, I can get 6 pairs of these selenoids for the price of new ones (which take 3 weeks to order). I can see how you got the impression that I was gonna just tear stuff apart

Later....

Don't waste your time on a bunch of used sensors. That's a huge waste of time.

If you turn the key on with the engine not running, do you hear the carb ticking? If you do, then the mixture control solenoid is good.

A TPS is less then $20 new. Why go to all the trouble of fiddling around with a bunch of old crap that is just as worn out as yours, do all the work of swapping it, only to discover that what you put in is as defective as what you had in the first place? It should be no problem to find one, millions of cars were sold in Canada that use that same part (AFAIK all GM computer-controlled carbs use the same one - Buicks, Olds, Chevy; 6-cylinders, V8s, 4-cyl; A,B,F, & G bodies; etc.). It's not a dealer-only item or anything. Virtually any parts storre will have it in stock.

IIRC the pins labelled 5 & 6 in that diagram are the ones you need to jumper to read the codes.

Disconnecting the knock sensor will usually set a code.

Most often, an intermittent light, especially if it comes on after 10 minutes or so of driving, then you can turn the key off for a couple of seconds and turn it back on and it goes out, then comes back on 10 minutes later, is a bad coolant temp sensor or its connector (a real POS). It's got a yellow and black wire, on the water outlet where the top radiator hose hooks up to the motor. New ones come with a better connector to replace the stupid one the car came with.

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"So many Mustangs, so little time..."
ICON Motorsports

RB83L69,

I think you are on to something with the temperature sensor. I noticed that the clip is broken, and the sensor is just pushed in there. However, I did not have any check engine lights before. I guess it could be co-incidence that it happens now.

The light does come on after the car gets warm, and then intermittently goes on and off. That could coincide with the cycling of the coolant??? It does go off if you toggle the key on/off. So from what you said, you are right on in saying it is the coolant sensor.

On the coolant outlet, beside the coolant tempurature sensor, there is another sensor. That one is connected to a vacuum line. What is that sensor for?

As far as reading my computer, even though I only have the four connectors, I will not wreck anything by jumping pins 5 & 6?


Thanks alot,
Draug

The other thing on the water outlet is the ported vacuum switch for the EFE (heat riser).

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"So many Mustangs, so little time..."
ICON Motorsports

The other thing that could cause an intermittent code throw is an EGR problem, espeically if cruising at part throttle when the code comes on. If it happens only after a few minutes of idling then you're IAB valve could be out of adjustment or you could have a moderately bad vacuum leak.


[This message has been edited by Damon (edited July 20, 2001).]

Thanks guys,

So I have a few possibilities. I want to display my engine codes using the jumper technique. Will it not wreck my computer forsure, even though I have only 4 terminals for my hook up?


Thanks,
Draug

Yipee!!!

The car is back on the road! You were right on when you said the check engine light was coming on because of the coolant temp sensor. I jumped pins 5 & 6, and sure enough, code 15.

I have also tuned the carb, which is running real good. It seems a bit rich at an idle, but it is as lean as I seemed to be able to adjust it without having it ping at real low RPMs under power. Oh well, the car pulls hard right through all the gears.

Thanks so much for everyones help. I really am thankful. I have learned alot, and I know there is lots more to learn.

Glad to be able to help... I hate seeing people go through as much trouble as you were about to put yourself through, none of which of course would have been the slightest help. Computer controls aren't that hard to understand and diagnose.

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"So many Mustangs, so little time..."
ICON Motorsports