Idol Only??? 92 Z28 .305 Manual.......... Starts and stays running but not smooth as usual. Surges some and a little high about 900-100RPM. However it will not rev or drive. Touch the throttle, it spits sputter and sometimes backfires. It does not have any codes when I hook up my OTC Genisus. When I turn Key On Engine Off no dummy lights come on, only the SECIRITY light. Tach, oil, coolant guages all work. Will the Vatts allow it to run but not drive? Is this a sign of a bad ECM and or Prom? Also another thing I noticed was my oil temp reads -39 wich is what my CTS reads when it's unplugged. Does a 92 have a OTS? If so, will not reading it put the ECM in "limp" mode? Could limp mode made the dummy lights not do a self test? I know there is a lot to unpack but any help or opinions would be appreciated, Thanks. |
Re: Idol Only??? You might want to start with checking fuel pressure and ohm injectors. |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6304920)
You might want to start with checking fuel pressure and ohm injectors. |
Re: Idol Only??? The injectors should be in the 15.5-16.5 range. If they have a grey body they are problematic multecs. |
Re: Idol Only??? Your problem is fuel DELIVERY. Not, fuel "pressure"... fuel DELIVERY. The AMOUNT, otherwise known as the VOLUME, of fuel the system can flow (DELIVER), when the engine demands more fuel in order to create power based on the load placed on it (some sort of relatively greater fuel DELIVERY requirement); not, the pressure it's capable of delivering sitting in your driveway under NO load (near-zero to minimal DELIVERY requirement). You can use pressure as a proxy (stand-in, indicator, substitute) for evaluating DELIVERY, however. Tape your FP gauge to your windshield with duct tape or some similarly high-tech substance and drive around. See if you can correlate what you see on the gauge, with what you feel on your butt dyno. I.e., when the car falls on its face, what is the fuel pressure THEN? (as opposed to sitting in your driveway under no-load conditions) The pressure should STAY at 45 psi or whatever, even if you're accelerating as hard as the car can go, at as high a RPM as the engine can turn, for as long as that set of conditions remains in effect. If it doesn't, … you do the math. Your parts list is IRRELEVANT. If your fuel system isn't DELIVERING the fuel the motor needs, then, … it's INADEQUATE in some way. First thing you need to do is, identify the problem, in such a way that you can clearly see the difference when you get it fixed. |
Re: Idol Only???
Originally Posted by sofakingdom
(Post 6304940)
Your problem is fuel DELIVERY. Not, fuel "pressure"... fuel DELIVERY. The AMOUNT, otherwise known as the VOLUME, of fuel the system can flow (DELIVER), when the engine demands more fuel in order to create power based on the load placed on it (some sort of relatively greater fuel DELIVERY requirement); not, the pressure it's capable of delivering sitting in your driveway under NO load (near-zero to minimal DELIVERY requirement). You can use pressure as a proxy (stand-in, indicator, substitute) for evaluating DELIVERY, however. Tape your FP gauge to your windshield with duct tape or some similarly high-tech substance and drive around. See if you can correlate what you see on the gauge, with what you feel on your butt dyno. I.e., when the car falls on its face, what is the fuel pressure THEN? (as opposed to sitting in your driveway under no-load conditions) The pressure should STAY at 45 psi or whatever, even if you're accelerating as hard as the car can go, at as high a RPM as the engine can turn, for as long as that set of conditions remains in effect. If it doesn't, … you do the math. Your parts list is IRRELEVANT. If your fuel system isn't DELIVERING the fuel the motor needs, then, … it's INADEQUATE in some way. First thing you need to do is, identify the problem, in such a way that you can clearly see the difference when you get it fixed. |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6304930)
The injectors should be in the 15.5-16.5 range. If they have a grey body they are problematic multecs. |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6304930)
The injectors should be in the 15.5-16.5 range. If they have a grey body they are problematic multecs. So apparently I have 2 bad injectors? But would 1 injector on opposing banks cause it to not be able to rev up? I know that it will cause power loss but figured it would still be able to drive. Also checked and none we're shorted to ground. And yes they are the grey ones. |
Re: Idol Only??? I would be inclined to replace the injectors and see if the problem persists. You might want to contact southbay fuel injectors and get 19#hr replacements. |
Re: Idol Only??? Wil it rev with the two bad injectors unplugged? |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6305117)
Wil it rev with the two bad injectors unplugged? Also I have a zex Nitrous system and I usually just keep the nozzels set to 75 but I can shoot 150 so I'd like to go with a good injector and might as well change them all. Any suggestions? |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6305115)
I would be inclined to replace the injectors and see if the problem persists. You might want to contact southbay fuel injectors and get 19#hr replacements. |
Re: Idol Only???
Originally Posted by dmyruski
(Post 6305124)
Just unplugged 5 & 8 and ......... I love you! LOL idol has not changed but it will rev. I have a responsive throttle again. Any ryme to reason why or just something you picked up from experience with these old beasts? Either way, Thank you. Also I have a zex Nitrous system and I usually just keep the nozzels set to 75 but I can shoot 150 so I'd like to go with a good injector and might as well change them all. Any suggestions? some have experienced lean running with the Bosch 3s without ecm/prom retuning. There Delphi’s should be a direct replacement but costs more. or there is this option which I think is a direct replacement as well. https://www.southbayfuelinjectors.co...tors-1985-1992 |
Re: Idol Only??? If you do order from them try tg11 code at checkout. |
Re: Idol Only??? Any recommendations on someone good to get the prom tuned? |
Re: Idol Only??? I would do the necessary changes yourself. You need to look at the diy prom section and stickies. At the least get a moates.net extreme aldl and cable 1. You would also need tuner pro rt so you can datalog to see where your fuel trims are at. |
Re: Idol Only???
Originally Posted by Tuned Performance
(Post 6305132)
If you do order from them try tg11 code at checkout. |
Re: Idol Only??? The first step for tuning is to change the battery voltage offsets. That should put the fuel trims back inline . https://www.thirdgen.org/forums/diy-...0-voltage.html |
Re: Idol Only??? Injectors are in and everything is back together. It drives good but idle is still high and it surges a little, 900-1100ish. That's reading from my Computer not the tach. Also the throttle percent is changing from 0-3% but voltage is right around .54v. While I had it apart I cleaned the throttle body with carb cleaner and a rag. Should I pull the IAC and reset it maybe? Also I set my base timing since I installed the new distributor as well, and when pulling the car out the garage I realized I never hooked the brake booster back up so I definitely had a vacume leak. That shouldn't affect the base timing correct? |
Re: Idol Only??? The vacuum leak and higher idle while setting the base timing shouldn’t be effected. As long as you set the timing correctly with the est disconnected. As far as the high idle check for vacuum leaks first then set the minimum idle speed. After the minimum idle speed is set you can adjust the tps up to .67-.76 vdc. |
Re: Idol Only??? Sprayed carb cleaner around the intake and vaccume lines with no sign of an leak. Then I followed the idle speed adjusment procedure and when I plugged the IAC back in and restarted she went right back up to 1200rpm. Also to set the IAC I have put it In diagnostic mode but when I jumped the top two right hand pins, and turned the key on my fan was running constantly is that normal. And no CEL but that could just be the bulb. |
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