nitehawkjcb Posted February 25, 2011 Report Share Posted February 25, 2011 (edited) I've been searching for months now on an issue I've been having with my car. It's a 1996 Monte Carlo LS, with an L67/4t65e-hd. I had no issues with the engine/transmission for a couple years, but now the engine dies when I put it in reverse. It doesn't do it when the motor's cold, but once it warms up for 5-10 minutes, it will die instantly when I put it in reverse, and it will also stall rarely at idle in park. It's not studdering, it just DIES - much like when a crank sensor goes bad. I've already changed TONS of things. Crank sensor, TPS, MAF, IAC, fuel pump, all fuses and relays. The motor runs very good, it just dies in reverse primarily. Now, my questions: The remaining problems I THINK it could be are: -Transmission related (vac modulator, TCC solenoid, clogged line) I do have a P1811 (long shift), but I've had that code since the motor install. -Cam sensor -ICM -Wire shorting out I don't know what else to do - I've gone through wires and just can't find one that's grounding out. Fuel pressure is good. Please, if anyone has encountered anything similar to this issue, PLEASE, let me know! Edited February 25, 2011 by nitehawkjcb Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted February 25, 2011 Report Share Posted February 25, 2011 a 4T65 has no vacuum modulator, it has a pressure control solenoid. what all codes does it throw, other than P1811, which BTW, you should get fixed, that forces maximum line pressure IIRC. Quote Link to comment Share on other sites More sharing options...
nitehawkjcb Posted February 25, 2011 Author Report Share Posted February 25, 2011 Thanks for the info on the pressure modulator - I don't know much about transmissions, I was going based off my Monte Carlo manual, I figured it'd mention something about 98-99 Z34's not having a pressure modulator. The codes that are thrown now are 2 different EGR codes, my EGR doesn't work and I'm running it unplugged, the car didn't have this issue when the EGR went bad ages ago. A couple EVAP codes which I've had since the motor was installed, a MIL indicator lamp code (the bulb just blew the other day). Now something else that's kinda weird - unless the timing was absolutely impeccable, lol, when I was testing on the car earlier, the motor was of course dying in reverse. Weird part: if I could get it in Drive before the motor completely died, it would idle back up. Maybe check the connections under the shifter? It's not the neutral safety switch either, already replaced it. Maybe off topic - but could a misadjusted brake switch cause this? I doubt it could, but I've heard weirder things. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 25, 2011 Report Share Posted February 25, 2011 Check your grounds under the hood. Sounds like an old Pontiac I had once...you're grounding through the engine mounts, and when you put it in reverse, you've lost your ground. It really could be that simple... Quote Link to comment Share on other sites More sharing options...
nitehawkjcb Posted February 25, 2011 Author Report Share Posted February 25, 2011 Check your grounds under the hood. Sounds like an old Pontiac I had once...you're grounding through the engine mounts, and when you put it in reverse, you've lost your ground. It really could be that simple... That's the thing, there are only two different grounds in the wiring harness, one on the transmission and one by the ICM, and both of them are good. How would it lifting off a motor mount cause me to lose a ground though? Thanks for your input, I'm willing to try anything at this point. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 26, 2011 Report Share Posted February 26, 2011 A common problem is the two grounds you mention are poor, or suspect. Electricity always takes the easiest path to ground. If the wire grounds are not good, any metal-to-metal contact between the engine and chassis can then effectively become the ground....like the engine mounts in some cases. Quote Link to comment Share on other sites More sharing options...
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