Missing lt1 power help

[Casey_SS]

Just remembered another LT1 nugget - the coolant temp sensor in the water pump is used as a critical input for fuel & timing calculations. Both the sensor itself and the pigtail it plugs into have been known to go bad and cause issues like this.

[GlennCMC70]

W/ the exhaust leak it had (Dan let me hear it at MSR-C) it was likely sucking in alot of oxygen and the O2 was picking this up as a lean condition and dumping fuel. It likely dumped so much fuel the O2's are now fouled. You fixed the leak, but that didn't clean up the O2's.
That is why I asked about new O2's.
Also I think Casey is on the right track as well.

[GlennCMC70]

Also, single wire un-heated O2's are dirt cheap. I replace mine prior to every annual dyno cert.

[RichardP]

Lots of good suggestions for things to try. Hopefully we will get it nailed down.

The overall curves on the dyno looked OK (i.e. didn't fall flat above 4K for example) but the entire curve was a squiggly line. It was very strange. Random misfires and such usually result in spiky lines.

All of the spark plugs looked exactly the same when we pulled them out. There was nothing to point to a single cylinder having an issue. We will keep working that idea, though.

Thanks for all the help. I'll let you know what we find...


Richard P.

[Adam Ginsberg]

Just remembered another LT1 nugget - the coolant temp sensor in the water pump is used as a critical input for fuel & timing calculations. Both the sensor itself and the pigtail it plugs into have been known to go bad and cause issues like this.

Ford's, in my experience, have the same issue. Additionally, a failed/bad/malfunctioning ACT will cause all sorts of drama. Whenever I get certain symptoms that point to a failed ECT, I'll replace the ECT and ACT, just because. They're cheap, and easy to replace.

Check plugs and plug wires (remember when you're original motor was down on power, oh so many moons ago?), and the O2's as already mentioned.

[Rob Liebbe]

Take it to Nationals - it will mysteriously gain the missing HP back.

[Al Fernandez]

Richard, if you need LT1 parts you guys can come up and borrow from mine. I like Casey's idea of verifying each cylinder is working with a temp gun and of validating that water temp signal going to the PCM. I've had individual wires quit and taking them off the opti to test conductivity is a giant hassle but the temps will show that. Sounds stupid but make sure the butterflies are opening all the way and that nothing (like a big pile of dirt) is plugging the intake!

[RichardP]

A bit too much on the tune up parts and actually correcting the issue resulted in us diving off the end of the CMC2 chart with three runs at 271. Ooops. I can deal with that though. Some more dyno time and a smaller restrictor should get us back in the box. Thanks to the guys at Houston Performance for squeezing us into their busy dyno schedule (all three times).

I appreciate all the helpful suggestions. A shop that Dan took it to found 7 of the 8 injectors clogged. A fresh set woke it right up. Not sure of the details on what caused that or how to prevent it in the future. The car came with a fuel cell. It has an external fuel pump with a filter before the pump and a filter after the pump. Both filters are these pimpy red anodized jobbers with replaceable elements. I have no clue what is currently in them but my research suggests that the filter before the pump should be a fine stainless steel mesh rated at 100 microns and the filter after the pump should be a paper filter rated at 10 microns. We will make sure they are fresh and proper before we head out. I’m sure we will get some spares while we are at it.

Speaking of spares, does anyone have a set of stock lt1 injectors lying around that we could throw into the trailer in case we haven’t figured out the root cause and need to do another swap at the track?

We head out Monday morning! Hope to see several of you there…

Thanks again,
Richard P.

[GlennCMC70]

A bit too much on the tune up parts and actually correcting the issue resulted in us diving off the end of the CMC2 chart with three runs at 271. Ooops. I can deal with that though. Some more dyno time and a smaller restrictor should get us back in the box. Thanks to the guys at Houston Performance for squeezing us into their busy dyno schedule (all three times).

I appreciate all the helpful suggestions. A shop that Dan took it to found 7 of the 8 injectors clogged. A fresh set woke it right up. Not sure of the details on what caused that or how to prevent it in the future. The car came with a fuel cell. It has an external fuel pump with a filter before the pump and a filter after the pump. Both filters are these pimpy red anodized jobbers with replaceable elements. I have no clue what is currently in them but my research suggests that the filter before the pump should be a fine stainless steel mesh rated at 100 microns and the filter after the pump should be a paper filter rated at 10 microns. We will make sure they are fresh and proper before we head out. I’m sure we will get some spares while we are at it.

Speaking of spares, does anyone have a set of stock lt1 injectors lying around that we could throw into the trailer in case we haven’t figured out the root cause and need to do another swap at the track?

We head out Monday morning! Hope to see several of you there…

Thanks again,
Richard P.

All I can say is that I wish you guys the best of luck. Give them hell.

I use this for a fuel filter:
http://www.summitracing.com/parts/FRM-HPG1

I have never had any issues from it. My injectors are the OEM ones in place when I got the 67,000 mile motor from the salvage yard. I've never had them cleaned. I'm at 263/309 w/ a 40mm plate in place.

[AllZWay]

Good News Richard on the found HP.

I do have a set of stock injectors, but I might have a problem getting them to you on time. Let me know if you don't find another set and we can work getting these shipped.