datsunlover Posted October 2, 2005 Share Posted October 2, 2005 I have been searching through the archives and I think I confused myself more.. Heres the thing.. I have a TBI 350 with a 700r4 in an 86 Mazda rx7. It's running ok, but I have a few problems.. which I think 'may' all be related. I know there are some guys here who really know the GM FI and wiring systems, so I'm hoping to tap into some of that knowlege.. First off, it's idling a little on the high side (no tach yet, but I'd guess about 14-1500 rpm) which ends up with quite a bang going into reverse or drive. Then it wants to GO and I have to really hold the brakes to keep the car stopped. I've heard that the TPS can be the cause of this high/iratic idle, but at $90 for a new one, I'd rather check evrything else first... Second; 1st gear lasts about 2 seconds, 2nd about 5, and unless I hold it manualy with the shifter in 3rd, it'll get into 4th way too soon. I've checked and adjusted the TV cable, and havn't had much change.. Also, this happens with very little throttle down. THEN, with some more throttle, the check engine light comes on. And it goes out when I touch the brakes. Third; When stoping, it doesn't shift out of 3rd/4th untill the last second. As I roll to a stop, it feels like 2 or 3 quick downshifts in a manual tranny. (actually jerks the car forward on the 2nd-1st shift!) I'm assuming that's the convertor not unlocking.. is that reasonable? Now.. I have a theory, but I'm not sure anymore after reading through some links and old posts.. (most are dealing with carbed non-efi tranny issues) I have the spedo 'working' in the car, but it mis-reads WAY to fast. In town it reads about 80kph, although I KNOW I'm not going that fast.. more like 40-50. (I'm actually hiting a speed governor at 200kph, and it's shutting down.. I'm thinking it's about 140kph actual) I have a speed sensor from the mazda spedo head (cable driven spedo, VSS runs off the back of the guage) wired to the GM computer, and I thought maybe THAT is causing most, if not all of my problems.. IE; the computer 'sees' 80kph (almost a highway cruise speed) and tells the tranny to get into a higher gear. But the engine RPM is low, and throttle position light, so it thinks something is very wrong and turns on the check light. Could this also cause it to not want to unlock the convertor until the last second? I thought about wiring in a seperate bit of wiring to the brake switch, or even to a togle switch to control the lockup, but tought that would confuse the ECU as well.. Any ideas? Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted October 2, 2005 Share Posted October 2, 2005 Third; When stoping' date=' it doesn't shift out of 3rd/4th untill the last second. As I roll to a stop, it feels like 2 or 3 quick downshifts in a manual tranny. (actually jerks the car forward on the 2nd-1st shift!) I'm assuming that's the convertor not unlocking.. is that reasonable?[/quote'] I'm not going to be any help on the rest of this problem but I would bet money that this is caused by your high idle (making this more of a side effect than a symptom). Quote Link to comment Share on other sites More sharing options...
strotter Posted October 2, 2005 Share Posted October 2, 2005 You may be able to get a lot of answers from the computer itself. 1st: What computer? TBI could be a '7747 or '8746 or other... 2nd: What error is it giving when the light comes on? (short some of the wires on the ALDL output to get the error codes). 3rd: If you have access to a laptop (ideally an older one with a serial port, but a more modern one with USB will work too), you can fabricate a cable to read the ALDL data out of your computer for about $5.00, then read the data with some free software (such as WinALDL, http://web.telia.com/~u60113744/software/winaldl/winaldl.htm) or others, depending on what ECU you have. 4th: You may have a hardware problem with a sensor, some wiring, or the IAC. You can check the IAC by unscrewing it (with key off), grounding the body of it, and turning the key on. It'll go through it's startup sequence if it's OK, sit quiet if it's dead. Plenty of other computer-ish things could go wrong too, of course. I'm assuming there's no vacuum leaks or mechanical problems. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted October 2, 2005 Author Share Posted October 2, 2005 Well, as for the ALDL, I HAVE one, but I'm unsure if I have wired it correctly.. I have one of those little cheepie 'scaners' that you plug into the ALDL, and it's suposed to flash the check engine light in sequences, to give you the trouble code. (BTW, my 'check' light is actually the 'exhast overheat' warning light on the mazda dash, I found the wire from the sensor on the passenger side floor, and wired it to the ecu as well as the brake switch.. but I can't see how that would cause this issue..) Thing is, if I plug in the scaner, and turn the key, the check engine light just comes on and stays lit. No flashes or anything.. Then, it seams like it buggers the ECU or something, cause the car won't start after. I have to disconect the battery cables and wait 10 minits or so.. About the IAC.. that's the sensor on the throttle body with the BIG arse nut holding it on? And what does it do for a startup sequence.. clicks or something? See, I know this problem(s) is something I have screwed up, because the engine/trans worked near perfect in the doner car; Nice idle, smooth shifting, and didn't stink of overfueling.. Quote Link to comment Share on other sites More sharing options...
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