jmabo205

iTrader: (1)

I have a 88 TII and there has been a problem that's been happening since i got the car tuned. it didn't happen a lot a first, but now its all the time. The problem is that when i start the car (first time, or after it sits for a while, cooled down almost all the way) to warm up its fine, i have to hold the pedal down to warm it up like normal, but when the car starts to warm up like around 65-69c degrees, when i press on the gas to go, it hesitates and bounces back and forth from 1k to 2k rpm. so i turn off the car and try again but hold the pedal down while starting to go to about 3k or a little more and then it works, but after a few seconds it drops by it self back to 1 and starts bouncing between 1k and 2k rpm. If i shut the car off, and let it sit so the temp rises to about 74c or 75c i can start it and drive normal, it goes away. I can't figure it out, i thought maybe air was leaking somewhere, but then the hesitation would be all the time and i can't drive the car at all right? so I'm not sure what happened after the car was tuned, but it never happened before. I really need your help with this, its driving me crazy.

MODS: PFC standalone, racingbeat exhaust, 720cc second injectors, grounding system, voltage regulator, sard fpr, walbro fuel pump.

Fijensen

I noticed that you said you "got the car tuned" if you didn't do it yourself; shouldn't you take it back to the place that did? They probably knocked a wire off, or something. I knock my oil pressure ind wire off every time I change my plugs. I never notice it til I'm driving down the road, and the oil pressure says 0.

arghx

iTrader: (3)

First, check out this writeup I did about a Power FC in a 2nd gen:

http://www.geocities.com/arghx/PowerFC.FC3S.Tuning.doc

who tuned it? did they actually hook a laptop up to it using the Datalogit interface box? If not, you didn't get your money's worth, as there are a ton of driveability settings that can't be adequately tuned without doing so. There are so many things it could be... INJ map, INJ vs air temp correction table, INJ vs water temp table, accel table...

Sometimes the stumbling you are describing could be due to an improperly set TPS or ignition timing that is too retarded (most likely because the CAS was not installed correctly). I presume you are using the Banzai Racing adapter kit with an s4 TPS. Go into your PFC Commander and go to Etc --> Sensor check. What does VTA1 and VTA2 say? Those wires should read the same voltage if you hooked them together, the details of which are in that writeup. With the key in the on position, engine fully warm but not running, they should read .7-1.0 volts with the throttle closed and 4.7-4.9ish WOT. If not, you need to adjust your TPS screw. If it won't get close to 4.7 volts WOT with the TPS set right you may need to replace your TPS.

Also, you should not have to hold the pedal down to warm it up unless the thermowax system and its coolant lines have been removed from the TB. Do you still have your BAC installed? What is your base fuel pressure? Most people have their FPR set so that it is 40psi with the vacuum line disconnected.

jmabo205

iTrader: (1)

I had it tuned at neptune speed by yoshi the owner, and yes he used the datalogit with a laptop. I probably mite take it back to him but i wanted to see if i can do it at home. I have to hold down the pedal because my thermowax isn't working, and my bac is installed. Base fuel pressure is i think at 2-3. I'll read that link your gave me. Thanks.

arghx

iTrader: (3)

he probably doesn't know as much about tuning a 2nd gen with a PFC. It's the same basic process (I have tuned both FD and FC) but there are a few little differences, with the TPS being an important one.

If you care about a stable cold idle you need to get your thermowax working or bump up your hot idle speed enough so it doesn't stall even when cold. I got so irritated at not having the idle stability of a thermowax that I put a stock throttlebody back on along with that pesky coolant hose.

jmabo205

iTrader: (1)

Arghx. well, i'm sure that he knows a lot, he specialize in rx7s and tuning for the pfc, and a lot of rotary heads in So cali go to him. I'm going to talk to him and see what he can do, but i'll check the car over again myself to see if some hoses came off during the tuning since it was running real hard, and check to see if i need to replace some gaskets. Anything else you suggest to check besides that and the vta settings? Oh ya, he said try and disconnect the bac valve to see what happens, but it was still the same. Thanks for you help and please if you have anymore advice it will be much appreciated!

dougiepants

thanks for this post guys.