DRIVER456

I put new injectors in,Went from ID2000's to DW 1200cc injectors,Now the car is not making boost,It goes from 3-4lbs down to 1lb by the end of the 1/4 mile when it should be making 7lbs. Is this just coincidence or do I have a boost leak.I did throw a belt last week,But I don't see any damage.My secondary fuel pump is working,Checked that before I put the car away.What else can I check.

silver408z

Sounds like a boost leak, injectors shouldn't hurt boost. You could have a boost leak around you the injector seals I suppose.

Shoaf85

Agreed sounds like injector orings to me. IF that's all that you changed....

stevieturbo

There is no way injector o-rings would cause such a huge leak, without the engine running like ***** too.

And it would be helpful if you detailed where your boost comes from....and perhaps what other work if any was done when you changed injectors.

You mention a belt, so it's a supercharger of some sort ? And when you fitted a new belt, did it perform ok ?

And presumably you had the ecu re-tuned to suit the new injectors ? Did it perform ok at this stage ?

DRIVER456

Yes its a supercharged LS7 in a C5,I found 2 cuts in one of the intake hoses but they don't go all the way through,I'm checking everything this weekend.I put all the injector data in,car ran/idled fine,kept adding throttle % to run the 10.00 index and just stayed in the 105-115 KPA would not go past that.Just kind of strange,All I did was change injectors.Last week my alternator pulley came loose and the belt came off but did not damage anything,I thought maybe it cut the intake hose but it did't.I'll find the problem some how

Shoaf85

Ive seen LS1 sized injector orings in a LS2 manifold before and it acted very similar. The car however would not idle below 1000rpm regardless of what you commanded so we figure it out pretty quickly. Needless to say it was quite a large leak as all 8 injectors were this way. Just a simple check to see if this is the case would be first on the list.

What about bypass valve? Is the vacuum line still attached?

DRIVER456

Thanks for the replies,I'm going to check injector o-rings and do a compressing check also this weekend I'll report back

Big Jt

did you mean 22-24 lbs and down to 21??? if not.. why do you all that stuff anyways??

DRIVER456

Would a broken valve spring cause boost to bleed off

stevieturbo

A broken spring would be giving worse symptoms than boost not getting as high as you think.

And dont think you've answered anyones questions yet ? Have you checked belt, all pipework etc ? Does it even run properly ?

DRIVER456

Car runs great,Idles fine,The car still pulls hard the boost will go up to 4lbs then ramp down to 1 lb.I put a new map sensor,new blow off valve.New belt,piping is fine.I also did the smoke test and it only came out of the air filter.I guess I'll pressurize the intercooler next.I ordered a leak down tester,Just waiting for that to come in.

stevieturbo

Replacing map sensor is pointless without actually testing it.

And the symptoms you describe can pretty much only either be a boost leak from a pipe coupling or belt slip.

But if you're saying car pulls hard...does it pull hard and feel as it did before with higher boost, or is there also a noticeable loss in power when you see this boost drop ?

DRIVER456

I found the leak.The intercooler is leaking and also the IAT sensor was leaking bad.Thanks everybody for the replies

stevieturbo

You've found those leaks, but have you sealed them and confirmed that is the problem ? They look like fairly small leaks.

DRIVER456

It has to be the problem,The IAT sensor was leaking pretty bad.Those leaks still can't be good.The section I had plugged off would not hold air.

stevieturbo

Absolutely, leaks are never good, but it sounds like you've a huge leak ( or belt slip )

neverstop

I've seen the Siemens injectors leak like that with old ls6 o rings and aftermarket fuel rails. Katech sells some slightly larger injector O rings and they aren't really expensive anyway so probably worth a try but spraying soapy water on the injectors will show in a boost leak test so it's easy to try.

If you want to try and track them down yourself the size is 16mm OD, 4mm thick and 8mm opening.