campbellsoup24

Hello,I have something going on with my 93 GT and can not seem to get an answer from anyone?

Here goes, I have a 93GT with GT-40 crate motor, 24lbs inectors, and astock T-5 5 speed.
The issueI have is that when I am trying to cruz at a low speed (down my street) or typically under 45mph my car will sometime jerk back and forth? If I give it gas, push in the clutch or just let all the way off the gas it goes away? If I am cruzing at a lower speed but put it in a higher gear it tends to be worse. I can also slightly feel it when going down the freeway in 5th, its not near as bad but you can feel a slight surge back and forth? Not sure what to make of it, it never had this issue beforeI put in the different motor? Any help would be great!

Thanks,

Mike

mjr46

first thing I'd do is run a koer test and look for codes if none exist it may be a lean condition but that's just a guess..make sure no vaccum leaks exist

campbellsoup24

I am starting to think it could be a vacumm issue, but I think I just may need more vacumm? I have a rather large cam in it andI had to upgrade the brakes and go to a cobra booster to help with the pedal feel. The car is also very fumy, (would that belean or rich) I can't have it running in the garage because it will burn my eyes. I had it tuned by the#1 guy in Michigan so I don't want to question that he did it wrong? I may take it to the ford dealer and have him check the boost for me?

Thanks,

Mike

Alero99

does it smell like fuel... then your running rich, possibly not an error of the tuner maybe somthing internal went wrong... best thing to do is bring it back to the guy who tuned it and have him check the car over.

mjr46

what cam are you running??

FoxGT

could be running too lean at cruise condition like mjr said. Mine does it when I cruise aswell, but I have my iat sensor just laying on the lower intake until I can get time to drill/tap a hole for it in the lower intake (explorer intake [8D])

Any idea what your base timing is set at?

campbellsoup24

Thanks for all the responses guys, It does kind ofsmell like fuel, more on the strong exhaust side of it. As far as the cam goes, I ordered a GT-40 Crate motor from summit and it said it had the E-303 cam in it. I have not heard another mustang with the same cam yet, but I have never heard another mustang with this type of sound before? It has such a big lob at idle it sounds like a big block chevy! I have thought maybe it was a vacuum issue, butI do not know how to get better vacuum out of it, I have allready checked for leaks and found nothing? I guess I could take it back to Alternative performance but I think they may charge me an arm and a leg to look at it? I guessI could just run my problem by them and see if they have any info for me? Not sure what te timing is at?

Thanks,

Mike

campbellsoup24

I took it by the speed shop and was told to try spacing my spark plug gaps to 35-40,000 ths. have you guys ever heard of anything like this causing this issue? Everything else seems to be ok? I will try pulling them out and checking the spacing on them, hopefully that will help, otherwise I need to take it to get looked at.

Ryan5.0

It sounds to me like that driveline lash so common in 5.0s. Mine does it and so do a lot of others. I don't think it is engine related. There was a post with numerous responses on the subject several weeks ago. Try a search and maybe you are having the same problem.

aode08

run codes, thats not normal mine did that, the TPS was fluctuating voltages in realtion to the actual position of the throttle body butterfly angle, but did not set a code.

The tps also had dead spots.


with a volt ohm meter, green wire pos, black neg, key on eng off,.

the tpsmight show,.90-1.05 , slowly increase the throttle and the voltage should move up very smooth and NOT FLUCTUATE(high to low or show zero etc).

Now slowly decrease the throttle, the voltage should get lower and not jump all around or show a zero.

Any of that, and thats your issue, code or not.