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Mike S.
Mike S., ASE Certified Technician
Category: Pontiac
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Experience:  ASE certified
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I am having an issue with my 95 Pontiac firebird. When you

Customer Question

Hi I am having an issue with my 95 Pontiac firebird. When you make a right hand turn it acts as if it has no gas... just jumps and sputters.. when you straighten out it runs fine. It has a full tank of gas as well.. Yesterday took it out after checking for shorts in the electrical and I just kept it punched rather than than letting up once it started sputtering.. lots of knocking, and I got a check engine light that came on. I think I set off the knock sensor... then amazingly the car ran great... did right hand turns with no issue anymore.. the only thing I noticed was that the AC stopped blowing cold.. drove it for a good 15 min and other than the light and AC the car was fine. I turned it off and back on and the code went away.. ac started working and car started sputtering though the right hand turns. So my guess is that its a sensor feeding data to the computer.. tried disconnecting the Mass Air, it gave me a check light but still sputtered. The car is odb1 and not throwing any check engine light other than the one that I set off.. Lt1 V8 with Automatic trannie.
Submitted: 6 months ago.
Category: Pontiac
Expert:  Mike S. replied 6 months ago.

Check for a busted motor mount. Raise the hood and watch the engine as you place the parking brake on firmly, place one foot firmly on the brake, place the shifter in drive and with the other foot rev the engine and look to see if the engine lifts up off the frame more than an inch. Then check the other motor mount by doing the same in reverse.

Customer: replied 6 months ago.
took it to a repair shop, and nothing is wrong with the motor mounts. They say its something electrical any ideas? As I had in the original description... "When you make a right hand turn it acts as if it has no gas... just jumps and sputters.. when you straighten out it runs fine. It has a full tank of gas as well.. Yesterday took it out after checking for shorts in the electrical and I just kept it punched rather than than letting up once it started sputtering.. lots of knocking, and I got a check engine light that came on. I think I set off the knock sensor... then amazingly the car ran great... did right hand turns with no issue anymore.. the only thing I noticed was that the AC stopped blowing cold.." The shop said the car went into a survival mode... so what that do to correct the right turn issue?
Customer: replied 6 months ago.
As in original desciption... I turned it off and back on and the code went away.. ac started working and car started sputtering though the right hand turns. So my guess is that its a sensor feeding data to the computer.. so what happens in survival mode that resolved the issue... my guess is the survival mode tells the computer to ignore input data from some of the sensors.
Expert:  Mike S. replied 6 months ago.

You don't set off a knock sensor, the knock sensor retards the timing when it detects a knock. You can test it with a timing light. Watch the timing marks as you tap on the engine block right near the knock sensor and you should see the timing retard when you tap.

The reason I thought maybe motor mounts is because if the engine lifted up going around a turn, it might pull on a wire or fuel line, etc making is misfire.

Is it sputtering when making a sharp right hand turn or will it also sputter just in park and turning the steering wheel to the right?

What I would do is hook up a fuel pressure gauge, a voltmeter to the alternator, a tachometer if it don't already have one and anything else you might have and watch these items as you make it sputter and try to catch whatever it is in the act. The tach would should if the ignition is loosing primary voltage, of course the fuel pressure gauge if the fuel pump is shutting off, the voltmeter is the alternator quits, etc.

Also, retrieve them codes.

I don't know what " survival mode " is, perhaps lymp mode.

Customer: replied 6 months ago.
Once the check engine light came on due to all the knocking is my guess ... due to my holding the accelerator down and just letting in jump and jerk to a near stop(once you let up off the accelerator it take about 5 seconds to recover and starts idling and acceleration again correctly). The car ran fine with no issues anymore other than the A/C compressor would not engage. I drove the car for over 15 minutes making all sorts of right hand turns and no issues. As soon as I turned off the car and then back on the Check Engine light went away and it started jumping though the right hand turns. Issue only arises when the car is in motion, going into right hand turns. So whatever happens when it goes into "lymp mode" fixed the issue until I turned it off and on and the Knock sensor reset.
Expert:  Mike S. replied 6 months ago.

I would still try to hook up as many testers that you can find and try to catch whatever it is in the act. It might even be an ignition timing issue, so check the wires coming off the ignition/distributor, if it has one, whatever you might unhook in order to set the timing, make sure that is good and tight.

Expert:  Mike S. replied 6 months ago.

I just read something very interesting, "The base ignition timing on these vehicles is preset when the engine is manufactured. No adjustment is possible. Timing advance and retard are accomplished through the ECM/PCM with ignition control and knock sensor systems."

With that done said, it appears to me as though you may have a problem with the ECM/PCM. but I would test that knock sensor like I said, see if the auto-parts store has an ignition control module tester and if so, have them test that one and last but not least, replace that ECM/PCM.

There isn't any tests for them.

Expert:  Mike S. replied 6 months ago.

Have you decided?

Expert:  Mike S. replied 6 months ago.

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