DG Gordon

I installed yella terra rockers yesterday and from my previous dyno lost 15 rwhp and 15 tq. When installing them I also changed plugs from TR6s gapped at 35 to autolight platinum gapped at 58. The car was also low on fuel, reserve fuel light on the whole time on the dyno, I dont know if this could mean anything or not.
Need some opinions please.
Thanks DG

HumpinSS

iTrader: (1)

The PCM adjust for low fuel conditions fill the tank up and try again

DG Gordon

I was wandering about that but 15 hp, I was hoping to get at least a 5 hp gain from all this.

HumpinSS

iTrader: (1)

IIRC the PCM cuts fuel as it gets low to help avoid running out of gas but i may be mistaken

JPR

Same dyno? compair the SAE correction from before and after too. Only other thingg I can think of is possibly too much preload?

JP

DG Gordon

Same dyno same corrections. I torqued them down to 22# and turned it over and retorqued them again.

DaleMX

iTrader: (4)

I had to use the shims on mine.
http://www.ls1howto.com/index.php?article=21

DG Gordon

Thanks I read your article very helpful.
However I was hoping everyone was going to tell me`that it was a gas issue.

Slowhawk

iTrader: (12)

I would guess the low fuel or too much preload.

JxxxOxxxE

iTrader: (1)

I think that once you get so low on fuel, the PCM switches to a low octane table for fuel delivery, like stated before for saving gas...

With over 1/4 of a tank, you will be in the high octane table...I think anyway....

White_Hawk

iTrader: (3)

Personally, I would put those NGK plugs back in before messing with the rockers. I have had bad experiences with platinums but I have always had boosted cars too. It seems that the pin sized platinum electrodes have a tendance to blow out of the plastic retainer when you get a little spark knock... Just my opinion though.

-Geoff

Colonel

The computer DOES NOT go into fuel saving mode (no such thing) when the tank is low. You're already at 14.7:1 during closed loop and leaning out the open loop would only cause detonation which is neither good for saving fuel nor for your engine. The idea about being low on fuel hurting your power started when someone noticed a power increase after filling up the tank. This does happen in cases where you have KR (whether false or real.) The computer goes into low octane mode when it detects KR (again, whether false or real. Ask me the difference if you don't know.) When you fill the tank, the PCM assumes that the KR was caused by low octane and it goes back to the high octane table (to begin with. Once it starts detecting KR again, it goes back to the low octane table.)

Anyway, just thought I'd clear that up.