motorheaddown

For months, I've been chasing a phantom ignition problem that's prevented me from moving forward on tuning the car. Well, today I found a purpose for dynos.

All my tuning has been on the street or highway with the hood obviously closed. There's really no need to hit a dyno when tuning tuning fuel with the AEM. Once the fuel is dialed in, the dyno is useful when adding timing. Today, I stopped by JP Importz for their dyno day and made some pulls after the dyno was setup. On the first pull, I noticed a jet of mist coming out of the engine bay. Huh... hey Derek (5sp_sc300), what the heck was that? He stood by the engine bay and helped diagnose the problem.

Even though I installed new injector insulators, the seal on injector 2 would blow open above about 11psi of boost. I was a gnats fanny from yanking the motor. All this time, it was boost blow-by. I just never saw that problem with the hood closed. Fortunately, the cylinder wasn't toast; however, the compression has suffered a little bit.

Thanks to JP Importz for setting up the dyno. I understand it was a successful event. It was worth the fee just to find that @#$!@$%#$% problem.

Now, I don't feel so bad making 300rwhp on 5 1/2 cylinders at 11lbs of boost.

-scott

Angel

So ... did you slap in the race gas and high boost or what !?!?!?!

awj

Wha? With it blowing by like that? Probably not. Interesting to see that it wasn't even ignition after all. Glad you got it sorted. Now fix it.

motorheaddown

Nah... we tried pushing the insulator back in, but it would just pop out. Plus, I have a completely new setup ready to go in (sp mani, tilton, b&p fmic, 95lb injectors), and I've held off until I figured out what the problem was. Now, I feel comfortable putting that stuff in knowing what the low numbers were for. So, it'll be a couple of weeks before I hit the dyno again. However, I'm going to TX2K4, and the car has to be ready by then.

I now realize why the car ran so well cold. The insulator would cool down, shrink, and temporarily seal the injector until the car reached temperature. Once at temperature, the insulator would become plyable and break its seal.

Just after warming up, I tuned the car on 18lbs of boost and could cut the wheels loose in 1st/2nd gear on boost alone without dumping the clutch. After the first pull, however, the performance would go to hell, and I could never figure out why. Well... now I know.

-scott

Dew23

iTrader: (1)

Good for you i have been watching your trials with your setup and i am happy you are making headway.

motorheaddown

Well, everything makes sense now. Months ago, I noticed a brown discoloration (sp?) around the valve cover. I thought it might be an oil leak even though I replaced the valve cover seals. Duh... it was gas vapor escaping from the injector that would evaporate/burn when it made contact with the valve cover.

-scott

Lex Luthor

That's wild, real glad you got it pinpointed Scott.
- Jon