I preface this by saying that this is my first EFI car...

I recently became the proud owner of a 94 3.4l camaro to put my 83 Z28 to sleep for a while. I got everything running fine, but Ive noticed that once I get past maybe 1500rpm, my power drops off. If its a weak motor, I can understand that.... What I CANT understand is why at EXACTLY 3400RPM, I get a power boost! A push you back kind of boost.

This doesnt seem normal to me....and no Im not running a turbo. In fact, it feels like the whole car is a bit sluggish (until 3400rpm). My assumptions are something in the EFI system is bad....but I have no clue about that. And I cant jumper my ALDL port to get any trouble codes (either its not working, or its ODB1.5).

Any help would be appreciated.

Thanks

 

Looking at some newsgroups ive found similar surging problems from people....one was a bad cap/rotor, one was a bad MAP sensor.... I dont want to go replacing everything cause Im TRYING to save money to throw at my 3rd gen!

 

well welcome to the wonderful v6 family. I got a 94 3.4 camaro. Couldn't be a bad cap or rotor since its a distribuitorless ingintion system. If it was a map sensor it would be doing through out the rpm band. Does it do in while the car is sitting or does it have to be under a load to get it to act up like that? Also can you get a datastream from all the input and output sensors while it does it? That will me alot in narrowing it down to certant possiblities. Because from what you are describing that engine is doing something that I'v never head of before.

 

X2

oh and jsut for the record, i cant get the jumper wire trick to work on my 3.4L either (although i have a scanner so its not a big deal for me)

 

I guess it would be difficult to change the cap and rotor then, huh?! I only have this problem at WOT, I think. Im wondering if it might be a problem with the transmission. What about the possibility of injectors not flowing right until high rpm? I dunno... I seem to have power off-the-line, but when Im cruising, and floor it, my powergoes up (as it should) then struggles to make it to 3400....then it kicks in again.

Very confusing...

 

mmmmmmmmmm does it always happen at wide open throttle? Under any conditions? If so I would lean towards the throttle position sensor starting to go bad. But again its hard to say with out some good data stream data to look of off. Like I said before if you can get a data stream of every input and output sensor on the car while its hapening I can more than likely pin point the porblem.

 

whats the jumper wier trick?

 

It seems to happen while Im running...at any time/temp... If Im cruising along, and I floor it, my tranny will kickdown and I will have no power until 3400. I could see how the TPS could be an option. I guess possibly that the quick change in the throttle isnt detected correctly and Im basically flooding the motor until I reach that "balance point"....Is that what you were getting at?

I also notice that I occasionally get what feels like a misfire where my car "bucks" a little. Only happens a couple times. I dont think this is related tho, as I think this is a coil pack going bad.

Its still amazing to me that I can watch my RPM and say "NOW" when Im going to get my power!

 

On older ODBI cars you can put a paper clip across the top right two pins of your ALDL to send your computer into diagnostic mode...e.g. the Service engine soon light flashes out its code....

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not really if its your thorttle position sensor sends a single to the computer and lets the computer know how much air can be passed into the engine, hence its name. But when you floor it to WOT the computer goes in what is called enrichment mode. Bascialy its using only the throttle position sensor, air intake temp, and coolant temp, and map to determin how much fuel to dump into the engine. And if the TPS is going bad the computer will not use that sensor's signal in the equation for the fuel dilevery. But with out that one variable the computer might not be allow the porper ammount of fuel in, either too much or not enought. Like I said get me a data stream and I'll get you a way better answer just telling me the symtoms like this is just play guess and check and I really don't like doing that I just like to figure out that the bare minimum the car needs to be able to run fine again. And about the pin trick it I think you have to jump the upper right hand corner and lower left hang corner together or either the lower right hand corner and upper left hand corner of the DLC to get the check engine light to flash the codes like you are discribing but its different for nearly every OBD1 car out there so its hard to say. If you are interested in that I say google it and see what comes up.

 

To get this datastream, do I need to make/buy an ALDL cable? I assume the 8129 baud aldl pin should give me the data in realtime, correct? If so, I'll probably make the cable this week sometime.

 

not sure the only way I know of getting a data stream is by having a scanner capable of looking at all the sensors signals. Ask around your area to see if any shop has an GM obd1 scanner that can export saved data streams, either straight onto a computer or on to some kind disk that you can take with you and then upload on your computer. YOu might wanna look around on the net there has got to be a company that sells software that you can buy that you load onto your computer and use it as a scanner for your car.