Hello! I’ve put a lot of work into my car over the last couple weeks, including cleaned injectors, new fuel filters, replaced vacuum lines, and new manifold gaskets. Previously I was having some idle problems and trouble on hot starts, and after everything I’ve done it was running perfectly for a couple days, started quickly every time, very stable idle, warm up system works well and rpm’s settle at around 750 like they should, and best of all my engine felt more alive than it has since I’ve owned it. Well I decided to go for a little drive today, started off well until I noticed when coming to a stop or letting off the clutch from load my rpms would drop well under idle speeds then bounce up past 1k before settling at 750. This was a little concerning at first, but then as I was getting out of gear and slowing down my engine full on stalled, and idk if it was just paranoia or what but I felt a little low on power after that too but I’m not sure. It didn’t happen again on the drive back to my garage but the bounce happened about 1/3 times in got out of gear, also felt like revs were dropping faster between shifts. I’m pretty damn sure I don’t have any vacuum leaks anymore, and i don’t think fueling is an issue either, any ideas? Thank you

 

It may be vacuum related but not a vac leak necessarily. Whats your brake booster like? You had mentioned this occurs coming to a stop. Might give that a thorough check. Are you still using all the solenoids?

 

Brake booster was a thought I had and I did manage to track down a new one, like a year and a half ago brake fluid started disappearing without any leaks and then one day just stopped, also the one on the car is rusting out the bottom now so I figured brake fluid probably leaked up in it. I did think that may be a cause but when the cars off the pedal stays hard if I pump it a bunch so I’m not sure. Also I’ll do some more investigation but I think it was happening when I wasn’t on the brakes as well

 

Hi,
I am installing my 3rd engine into my 88 GXL.

While I was going through everything on the throttle body, I found the delay valve had come apart. This valve is in the vacuum line from the diaphragm to the thremo valve.

Its purpose is to slow the closing of the front secondary throttle plates, I like to think of them as a form of a choke.

Once the water temp is above 140 degrees the plate should be fully open at all times.

Below 140 degrees it acts as a choke and is partially close at hi vacuum conditions. If the delay valve is worn out, the front plate closes too quickly and possibly cause the symptoms you are having?

If I am off base with my reasoning please let me know! The delay valve is still available for about $45