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- #581
ChasingSand
Well-known member
- May 5, 2021
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Spray some brake cleaner around the intake manifold and listen to see if the idle speed increases.
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Yep, I did that. I couldn't pick up any changes in the idle when I sprayed all around there. Maybe I just missed the leak location. I went ahead pulled the intake off to have a look and the gaskets seem to show some fluid on them from when I was spraying, but it could be my imagination.Spray some brake cleaner around the intake manifold and listen to see if the idle speed increases.
I had a similar problem recently. I won't go into details because it will just confuse things, but we switched to dbw throttle body and fixed a lot of issues. I think my stock throttle body was just worn out. This was after replacing the iac, checking for leaks, etc.More info: I can start it, put my gloved hand over the throttle body and it immediately dies, so no vacuum leak.
If I remember correctly the fan trigger on the harness on mine is a ground switched wire.Thank you for the suggestions. I'm curious why the drive by wire throttle body worked better.
I have an inline fuel pressure gauge. It's reading 80 psi. I'm using the same fuel pump that was in my buggy that worked fine for the 2.2 Ecotec I removed, but that is something that is different in this setup from how I bought the engine. Could the fuel pressure be overwhelming the fuel injectors, causing them to shut off, turn on, shut, turn on? Fuel is returning to the tank via the return line, but maybe not enough??
I thought I was on to something when I remembered that the engine as I got it had a wire coming from the harness that went to the fans (relay input). I wired my fans separately because I prefer to control the fans by a dash switch. So I thought maybe the engine doesn't know when it's warmed up and it's time to drop the idle, creating a high idle condition that it is then trying to fix (cuts fuel) then it goes back to high (adds fuel, etc. SO... I wired my fan relay input to that wire from the ECU/harness. The temp got up to 208 and the fans never came on, so I shut it down.
Then I tried adding the switch back in and I manually turned the fans on, sending 12v to the wire from the harness, no change. Still surges.
The saga continues. I'll tinker some more after the engine & I both cool down, haha.
Thank you for looking into that. I have replaced the original IAC with a new one, but I will do a good cleaning of the throttle body and IAC passage and see what happens.Pulled this from Odyclub:
update:
I cleaned AIC valve again, it was drenched in carb cleaner. cleaned and tapped with hammer. after it was dry, I sprayed some wd-40 and I saw an improvement - the internal "throttle" inside AIC was now closing completely. Cleaned and lubed it again. Installed all parts and the car's idle recovered to normal - 1100 on cold engine, and about 750-800 on warm.
OK, I will look into that. Thank you. The fan definitely should have turned on by 208 degrees. The wire coming from the harness was red, so was assuming it was either wanting or sending positive voltage. Wait... that was the color of the wire spliced in by previous owner. On closer look it is a green wire headed into the harness. Anyway, something to investigate.If I remember correctly the fan trigger on the harness on mine is a ground switched wire.
OEM fuel pressure is around 64Thank you for looking into that. I have replaced the original IAC with a new one, but I will do a good cleaning of the throttle body and IAC passage and see what happens.
Fuel pressure regulator costs about $140, so not replacing that unless needed. I found no gas in the vacuum line that's connected to the fuel pressure regulator, so I'm assuming it's working.
The other various sensors are cheap and if they weren't needed I'm happy to have them as trail spares anyway.
In case you ever want one, Mishimoto makes a lower temperature water sensor.OK, I will look into that. Thank you. The fan definitely should have turned on by 208 degrees. The wire coming from the harness was red, so was assuming it was either wanting or sending positive voltage. Wait... that was the color of the wire spliced in by previous owner. On closer look it is a green wire headed into the harness. Anyway, something to investigate.
The fuel pump I'm using is a Walbro GSL392, 255LPH.OEM fuel pressure is around 64
Lbs. I only run about 40ish at idle and I am running larger injectors.