Just wondering if any of you guys have gotten any datalogs of your cars. I've been having an issue at high rpm where it sounds like valve float or the engine running lean or something. So, I grabbed myself a datalog.

Looks like i'm getting over 100% duty cycle at WOT above 5600rpm. I can only assume that it's due to low fuel pressure. That's something I'll have to check into, just wondering if anyone else has a similar problem and is maxing out the injectors too?

Can't really help you with any info, but what are you running for a fuel pump? I don't remember if you changed yours out or not.

JAson Im getting the same thing for injector cycle. Ramped my fuel pressure up a little bit. But Its still to high. My guess is since stock rev limit on these cars is like 5250 thats why. Ill be getting bigger injectors. I notice when I do get in that top end and my duty cycle hits like 104% Power really drops off.

yea thats nothing. Ive seen some cobalts getting up to 160% idc lol. In short to fix your problem get bigger injectors and use hpt to fix the constant...problem solved.

Hmm we dont use HPT.
But yes bigger injectors are a must I have found.

Sorry guys cant even read that haha.

Z24 Speed wrote:JAson Im getting the same thing for injector cycle. Ramped my fuel pressure up a little bit. But Its still to high. My guess is since stock rev limit on these cars is like 5250 thats why. Ill be getting bigger injectors. I notice when I do get in that top end and my duty cycle hits like 104% Power really drops off.

Stock rev limit is 6250. I set the rev limit on MS at 6300. Looks like i'm gonna go turn it down a bit. Right now I do have it set to pull about 5* of timing at high RPM, which is probably why the engine hasn't popped. But i'm probably going to go out and drop it down to 5600 to avoid running it out of gas.

It's more likely do to the fact that i'm asking the STOCK fuel pump (thats for Shawn, since he asked) to push 60-80 more hp than stock since theoretically it takes X amount of fuel to make Y amount of horsepower, regardless of how many cylinders you have. I've still gotta check and see what the fuel pressure is, but it might end up being ok and i'm just running up to enough power where the pump simply cannot flow any more. Of course, that could also explain why guys with 2.2's aren't able to push amazingly high numbers for power without blowing the engine. Course, my pump also has about 150,000 miles on it as well, might be getting time for it to go anyways. So I might as well start looking into a wonderful fuel pump. yay (removing the gas tank sucks)

Patrick, just curious. I see that DutyCycle1 and DutyCycle2 are different. Are you running bank fire (i believe in MS it's listed as alternating) as opposed to batch fire? I thought about changing to that to see if it helped out at all to at least bring the duty cycles down a little bit.

Here's some added goodness. I don't stay on it too long when it starts to bog down. But you can hear it in the first vid a little big just before 55mph, and in the 2nd vid just before 80mph. It sounds like a rev limter, but it's not. Rev limit is ~58 in 2nd and ~88 in 3rd

Ya mine does that same exact thing. When it gets up to the high RPMs you can just feel it fall on its face. At first I thought it was just my restrictive small port intake manifolds but now hearing you are having some of the same problems I will be looking into possibly an inline pump because I dont think I want to drop the tank.

I was reading on grandamgt.com that they are using 02+ trailblazer injectors. injector swap.