shaking??

fastGTP01 · #1 08-22-2006, 11:39 PM

ok, i have an 01 gtp with a few mods(below) and i am wondering what this shaking is. the whole car shakes when i am accelerating hard and then as it gets in the higher speeds or i let off the throttle, it stops shaking. the tranny shifts normal and does not slip, so i dont think it is the tranny. but the shaking can be fairly hard at times then as i let off the throttle it smooths out. any help is appreciated thanks.

mike561 · #2 08-23-2006, 02:58 AM

mine did the exact same thing, turned out i needed new plugs and wires because the engine was misfireing, but it could be anything though, like a low tire or loose engine mounts im geussing.

rickisrad · #3 08-23-2006, 08:12 AM

I agree with Mike. I would start with the plugs and wires. If you have access to OBD 2 scan it and see if it is a misfire. I would also use some Lucas additive to clean the injectors. How long has it been a problem?

richtazz · #4 08-23-2006, 09:07 AM

I agree also. Get the car scanned (Advance and Auto Zone do it for free if the CEL is on). If it shows a misfire code, change the normal maintenance parts (especially if it's been a while) like plugs, wires, fuel filter, PCV, and see if it clears up. Start simple and work your way toward the expensive stuff. If no codes are present, I believe a fuel pressure test is in order to ensure you're getting correct fuel pressure.

BNaylor · #5 08-23-2006, 02:31 PM

I did not notice any re-programmed PCM module in your mods? Also, I noticed a 3.25" SC pulley. You could be getting knock retard (KR).

fastGTP01 · #6 08-23-2006, 10:07 PM

ok heres the story on the car....... i bought it on august first and on august 4th it blew up. the number one cylinder droppped a valve and it was under warranty so the dealership said put a new motor in, so i pick it up tomor. the mods are the ones i see on it, and i dont kno if the computer is reprogrammed or nething like that. but now its getting a new motor. thanks

BNaylor · #7 08-24-2006, 07:54 AM

When you get a chance remove the PCM module from the air box and see if you see any data labels indicating you have a re-programmed PCM module. The most popular are DHP, Intense and ZZP. I cannot comprehend running a 3.25" SC pulley without one. You need the modified spark advance and timing tables to run a SC pulley under 3.4". Otherwise you may have continuing problems even with the new engine. At least check it out so you can rule that out.

The last time I monitored knock retard (KR) with a 3.25" pulley without a re-programmed PCM the readings were off the scale like around 8 degrees or more which will destroy an engine over a period of time.

I think I suggested this to you before but get yourself an autoscanner gauge kit so you can monitor KR.

fastGTP01 · #8 08-24-2006, 06:47 PM

thank u very much, and yes i am currently saving up for one of them. i thnk it does have a reprogrammed pcm, because when its WOT, it shifts at 7000 rpm, is that a sign or not? thanks.

BNaylor · #9 08-24-2006, 07:23 PM

Quote:

Originally Posted by fastGTP01

thank u very much, and yes i am currently saving up for one of them. i thnk it does have a reprogrammed pcm, because when its WOT, it shifts at 7000 rpm, is that a sign or not? thanks.

7000 rpms? No wonder it is sucking valves. Out of curiosity what other valvetrain mods do you have. How many pounds are the springs? Hot cam?

Whatever PCM you have it is not a standard run of the mill. It sounds like a custom programmed PCM. Maybe the prior owner had a Powertuner or had a custom job from Intense or DHP. Your PCM is set to run Stage III mods.

My Intense PCM is custom programmed for WOT shift points at 6,250 RPM and the engine rev limiter for 6,500 RPM because I still have stock springs but 1.8 aluminum roller rockers. I'm conservative on my mods because I don't plan on blowing the engine.

fastGTP01 · #10 08-24-2006, 10:31 PM

yea i figured sumthying was up, well i think im going to go to a junkyard or somewkere and get a factory computer, so it doesnt shift like this one does because now i am going to have a stock motor. i have no idea wut else the motor had done to it besides rockers and valve springs.

BNaylor · #11 08-25-2006, 08:55 AM

If you are planning on running the 3.25" SC pulley with the new motor you might consider getting the PCM you have re-programmed for Stage 1 type mods or basic street mods. It doesn't cost that much. Around $99 for a DHP, $99 Intense and $80 for ZZP. The new programming will overwrite the old settings.

I hope it all works out for you. Let us know how it turns out. Good luck.

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