Compression and timing check.

[Scott4g63]

So I bought my 91 laser about 2 weeks ago and finally had the time today to check the compression and timing. Compression checked out good, 150 across all cylinders. When we checked the timing it was set at almost 30 degrees BTDC. So we set it back to 5 degrees BTDC, it idles a lot better but has a slight hesitation a top end. Could this be because the computer is relearning itself?

 

[Boostinsideways]

Sounds like a boost leak to be quite honest.

 

[Scott4g63]

Yea I was thinking that too.

 

[DSM1G90]

How did you do your timing, for 30BTDC sounds like the ECU was in control at the time, and you have to disable the ECU to set base 5* BTDC timing.

..prob why you're having that hesitiation due to the thing is now so far retarded...

 

[Scott4g63]

We followed one of the write ups on here to set the timing. Does the ecu get disabled when you pull the mpi fuse? Cause we had to pull that when doing the compression check.

 

[LiquidX]

You need to ground the timing pin that disables ECU control of the ignition timing.

 

[Scott4g63]

Yea we did that, that plug by the battery right?

 

[And_44]

Yep, thats the plug.

 

[Scott4g63]

So I can disconnect the battery terminal to reset the ecu also, correct?

 

[2ga4gb]

+1 on the boost leak. That's the only reason I can really think that it's either pulling timing, or breaking up on the top end.

 

[Scott4g63]

+1 on the boost leak. That's the only reason I can really think that it's either pulling timing, or breaking up on the top end.

Probably from my stock IC piping?

 

[2ga4gb]

It would make sense seeing how its not exactly the strongest stuff in the world, hard piping does wonders. Exactly how bad is it breaking up?

 

[Scott4g63]

Not bad it's noticeable but it seems to be getting better the more I drive it.

 

[2ga4gb]

If thats the case could be the ECU relearning itself cause it probly got mad you were messing with it. Best thing to in my opinion is see if it stops and if not check connections, fuses, and try to find even the smallest boost leak sometimes thats enough to make your car break up.

 

[Scott4g63]

Ok sounds good! Thanks!

 

[Spoolin4Ever]

How are your plugs?

 

[Scott4g63]

How are your plugs?

They are good, just changed them.