I have a 85 T/A with a rebuilt 350 TPI that has about 3K miles on it. I just swapped out the auto tranny with a 5 speed. When ever I accelerate hard I get this hesitation before it takes off. It happens between every shift(1st-2nd,2nd-3rd ect). If I accelerate normally I dont notice any hesitation. When it was an automatic I never noticed anything but an auto kind of slips between gear changes if you know what I mean. Thanks for any help you can provide.

 

i had a problem that was similar on my 92 camaro, and it turned out to be my clutch was slipping. What sort of clutch are you running, and how many miles on the clutch?? I'm kinda guessing it might be new, but how old is the pressure plate you have too??

Phoenix

 

Everything is new. The flywheel is old and was not resurfaced.
Could that be it or is it a fuel or ignition problem.

 

Do you have any sort of custom chip in there? I assume that you are running the stock 350/A4 chip in there. That could be your problem. Head over to the prom board and search for your drivetrain combo. The A4 chip with a manual trans can do some weird things.

 

I have a Hypertech chip in it. It was a 305 origanally but was rebuilt with a 350 block. Does the chip need to be reprogrammed because I now have a 5-speed? I thought the chip dosent care if its an auto or manual.

 

There are quite a few subtle differences between the T-5/A4 chips. You are only compounding the problem by running a 305 chip with your new 350. Basically the computer hasn't got a clue as to what it's trying to control.

What year TPI did you install? Is it MAP or MAF? I bet if you picked up the Craig Moates' software and the connector your ECM would show you that its all over the place.


Did you swap injectors, heads and all that fun stuff? I assume you did....

Ditch the Hypertech chip and pick up a stock 350 (A4 obviously) chip, i bet that will help a lot. Then research the PROM board and start to burn a chip. Or you can have one burnt for you, but thats not really the best way to go about things.

 

I purchased the car with the new motor already done. So I dont know exactly what was done to it. From what I understand they used the top half of the 305 using a 350 block. They did use new injectors and it is a MAF system. Also they installed an after market cam and a 52mm tb. The car is an 85 so how can I get a stock chip for a 350 with a 5 speed when they didnt have that combination to begin with? Can I use one from another year?
The motor runs great, starts right up, idles nice and generally accelerates fine its only when I stomp on it that I get this lag or stumble or whatever you want to call it.
Thanks,
David

 

There are 2 types of MAF systems. Cold start injector and without. The 89-90 did not used the cold start injector while 85-88 used it. I assume that the person put the chip in when the 350 was installed. I am surprised that they used the 305 heads, that means that you have a pretty high compression ratio.. if thats the case do not use anything but premium in her if you don't all ready. It wouldn't surprise me if you are getting excessive knock from the high CR and the advanced timing. I you can goto the GM dealer and order a 350 memcal and chip (i think it includes the chip, i am not positive), they are only $30 or so. Find out if it has the extra injector...its infront of the distributor i believe. You should also check what chip is in there. Find the ECM...its on the passenger sidebehind the "glove box". Take the lower panel out and you have to reach up and unclip it. Take the cover off of the ECM and find the part number of the chip. Give hypertech a call and ask them what year/model the chip is for, this way you at least know what you are dealing with. Let me know what you come up with.

 

You've got a new clutch but you didn't resurface the flywheel....bad...I did that once, clutch lasted me a couple months then, ate itself alive...I had to go out again and replace it. I made sure I resurfaced the flywheel though.