Timing problem? Lack of power.

Rob91

Registered User
I replaced the inlet manifold some time ago (because I damaged one of the bolt holes for the SC –stuck bolt.. :( ). After I had it back together I made a few runs with my G-tech and noticed I had lost about 20-30 RWHP (from approx. 200 to 175). From the G-tech data it seems like I loose power under WOT from about 2500 rpm. I checked everything, and ended up taking it apart again down to the inlet manifold but left it in place as I didn’t have new gaskets. But same result! Funny thing is that it runs great, idle is ok (perhaps a bit rough) and no codes! KOEO, KOER and cylinder balance test renders only 111 (system pass).
Now I’ve got a scanner (well spent money!!) and I’ve done some tests. The data in the table (attached picture) are from a test I did today (driving at 2000 rpm in 2nd gear and then floored it.

I wanted to check the base timing also (at idle), so I pulled the “Spout” plug: I expected the timing to drop to 10-12 degrees, but it raised to about 30 degrees and then gradually fell back down to roughly 21-22 deg. :confused: Should it do that??

Other info: TPS, ECT, ACT, IAC are new –and never made any difference.
 

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Do you have a chip? if I remember right the stock octane pin pulled 3 degrees of timing when pulled out. If you have a chip it depends on who did your tune and when it was done as some tuners have changed as they've worked. As far as the power loss goes, have you checked for belt slippage? One sign of that could be black dust around the snout of the SC.
 
Nope, no chip.
I pulled the "octane" plug also, but no change. Had at one time both the spout plug and the "octane" plug removed, and all it did was to increase the timing to roughly 30 deg and then slowly fall back to 21-22 deg. :confused:

I also tried to disconnect the cam-sensor, but same result (more difficult to start, but no difference once idling).

Ok, bedtime over here :) ,but I'll be back in a few hours.

Thanks, all answers and ideas are greatly appreciated!!!
 
was the engine warmer or outside air temp warmer , with the sc every 10 degrees warmer outside air temp equals about 10 percent less power
 
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Two things I noticed (which are out of the ordinary) from the data logs:

1) Your engine isn't going into "closed loop" at light throttle (cruise conditions).

2) Your TPS stayed pegged after you lifted (on coast-down).

Also, your O2 voltage seems all over the map at cruise conditions.

Do you have any stored codes in the computer?

PS. What kind of scanner are you using?
 
I might have a problem while logging (using an Autoxray 5000 scanner). When I get the streaming data (DCL) while driving they make more sense than when I try to log a sequence of data sets. Will try to reduce time between data sets, and see what happens.

1) Your engine isn't going into "closed loop" at light throttle (cruise conditions).
When viewing the DCL data it's in closed loop most of the time, except during cold start and WOT.

2) Your TPS stayed pegged after you lifted (on coast-down).
Will check the TPS -again..

Also, your O2 voltage seems all over the map at cruise conditions.
I expected it to do that, but it is rich at WOT (and that’s a good thing, or?)

Do you have any stored codes in the computer?
No codes...


What about the spout connector at the A/C pump? Shouldn't the timing be set to 10 degrees when I unplug it? Haven't checked the timing with a lamp yet (to verify the readings I get from the scanner) -maybe I should.

Thanks!
 
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