Setting Timing RB20

[Skym]

From what I understand unplugging CAS is when you want to prime a new or rebuilt turbo.

Idle rpm is based of water temp. Coolant temp sensor could be faulty.

Some have done a rough tune via adjusting CAS, FPR.

[BrianV8]

oh really, so would it make sense for the rmp to consistantly run cold at 800rpm and hot at 1300rpm? or would it be more irregular.

I'll try the temp sensor anyways to rule it out. Any idea what one is worth and what car is a match for one? EG 300zx 240sx?

And where abouts is it located?

[Skym]

It should be at 800rpm when engine is up to operating temp 70 degrees+. 1250rpm is when cold, like -10 degrees.

It's that or a faulty MAF, but there would be an error code for faulty MAF.

[BrianV8]

ya thats what i figured too, i could never understand y the idle was all reversed. I'll try the temp sensor though. I know its not my MAF because i recently replaced it. Car runs better now.

[Skym]

I think coolant temp sensor is located on the L part before top radiator hose.

[BrianV8]

Sweet thanks. I'll replace it see if that helps my idle at all.

[BrianV8]

I just looked at those sensors. One is the guage sensor and the other looks like a fan switch. Is that one that looks like the fan switch the ecu sender?

[nissanconvert]

you can come grab mine, i changed it out when i was trying to find my cold hesitation..

[BrianV8]

k sounds good to me. What did u replace it with? The 300zx had a different connector

[BrianV8]

Ok so i tried timing my car and the computer has the timing all over the place. I still need to know what to do to disable the electronic timing so the motor can hit base timing which i can actually tune?? Anyone know?? Thanks

[Skym]

As far as I know the gauge sensor should be the same sensor the ECU uses.

Make sure the engine is at the correct idle rpm and engine is up to temp. The idle rpm varying is due to airleak or similar that can make the ignition timing change. Look at the tacho (rpm) and see if the idle rpm is solid, if fluctuating too much, check for airleaks / loose intake hoseclamps, cracks in piping / intake pipe joiners, etc.

The engine normally idles at 800rpm, then down to around 650rpm (auto, manual) after a while, which is I think the rpm that the white sticker on front right side of bonnet / hood (under bonnet / hood) mentions when adjusting CAS. There should be auto, manual settings. 15 degrees BTDC (Before Top Dead Centre) for manual and 20 degrees BTDC for auto. Turning CAS left is advancing timing, orange mark is O and white marks are 5 degrees apart.

[BrianV8]

Ok i'll try that. I still have the problem with my high idle, i swapped out my temp sensor didn't do a thing. I was talking to my uncle (a mechanic) and he was saying on every car there has to be a way to disable the computer to set Base Timing. In his opinion just turning the CAS will not give you an accurate reading. And if the computer was taken out of the equation the motor can rev to any rpm it wants and it will not effect the timing. So thats why i'm kinda curious about all this.

[Skym]

Check that TPS is sitting on the idle contact.

You can adjust the idle rpm at the ECU, by playing with diagnostic pot (screw) and that should drop rpm to around 650rpm. But as far as I know you only do that before adjusting idle rpm.

[BrianV8]

OH what that screw on the ecu adjusts rpm?? I thought it was just a way to take it in and out of diagnostic mode. I guess i'll rip out the ecu and try that. I checked my tps and tuned it to factory resistance already so i know thats not the issue.

[Skym]

It's the manual way to put ECU into the mode to adjust idle rpm. Idle rpm is adjusted at AAC valve via screw.

If not temp sensor, it might be a sticky IACV valve (need cleaning).