Bogged under load after cold start

[Kevin]

Hi all. For a while now, if I start driving my DeLorean after a cold start, it gets a little bogged down while under load in 2nd gear. If I let it warm up for a few minutes first, which I usually do anyway, it's fine. I've attached a video so you can hear what I mean. As you can hear, 1st gear is fine, but once I get into 2nd gear I can't get the RPMs too high. I'm also going up a little bit of a hill at that point so the load is a little greater.

And ideas? Thanks!


http://www.youtube.com/watch?v=TtxTa-nXpAo

[Spittybug]

Sounds like your timing isn't advancing properly. Since it is temperature related, I would suspect the thermo vac switch in the Y pipe??

[sdg3205]

Mine has always done the same thing, but it doesn't bother me now because I drive pretty gingerly for the first 10 minutes. That old PRVs gotta last!

My car also doesn't shift as smoothly for the first 10 minutes. I just assume let it warm up, but I agree, there's always a solution to the problem and spitty is probably right.

[Kevin]

Sounds like your timing isn't advancing properly. Since it is temperature related, I would suspect the thermo vac switch in the Y pipe??

Thank you, Owen, that seems likely. I couldn't quite get my hand under there to see if everything's hooked up correctly, and I'm not looking to remove my intake anytime soon. But assuming everything's correct, if I feel vacuum going to the solenoid valve right after a cold start, then my thermal vac switch is likely borked? Let me know if that doesn't sound right.

[Jonathan]

I don't have a manual transmission, so pardon my ignorance, but would a vacuum leak of some kind cause this and show up more so in certain gears and less in others? In the auto trans, at times when you go from drive to park it will change the idle and I have had some folks mention this could be related to a vacuum leak. And one that is magnified with changing loads. Didn't know if the same applied in any way to the manual trans.

[David T]

The PRV doesn't run as well cold or warming up as it does when it is hot. It could run better though. Check all of the warm-up systems including the vacuum and mechanical advance and all of the vacuum hoses. I am guessing but it could be a bad Control Pressure Regulator. You can verify that with a pressure gauge, watching the control pressure as the motor warms up. It may also be due for a tune-up, changing spark plugs and adjusting valves.
David Teitelbaum