O-ring leaking or missing from bottom of injector... Huge vac leak.

[SIZEMOREMK]

So my boost gauge started acting flaky and I decided to check for VAC leaks.

I pressurized the intake tube using a PVC cap fitted with an airline to my compressor at 10-15PSI and found a huge pressure leak coming from the rear driver side fuel injector.

I removed the injector in question and could find no evidence that an o-ring was in there. I guess it is possible that it was broken, or halfway on and fell to the side or down in the intake, but I never seen it.

There was a little staining around the bottom of the injector, and I had a little bit of a raw fuel smell from time to time that I chalked up to lack of cats.

After replacing the oring there is no more leak, and the car is now throwing a slow O2 sensor code. I'm assuming this is because the car was tuned with this pretty bad vac leak. Throwing everything off. I would also imagine this is why it seemed that the boost has been low and seems that it takes it a good while to build any boost.

I'm curious if it is possible that the oring was never there? Nothing has been done to the intake or injectors since I've had the car, so this has probably been an issue for some time.

Anyone had any issues with leaking and/or missing injector o-rings?

[MMBLUE]

It is possible that the O ring came off and I/we forgot to put it on or, it was never there. After all. It was taken on and off more times than I like to remember.

A definite yes on the O2 code. Sounds like a new tune in your future. Or, maybe MartyO can give you some parameters to work/adjust in .

That explains the gradual boost climb. I have never been in another boosted MM so, had nothing to compare it too.

[martyo]

So my boost gauge started acting flaky and I decided to check for VAC leaks.


This is something that you did not tell me before or in the last few months since you have had the car back.

The boost gauge was not bouncing when it left the shop an you never told me that it was before this post.

I am even more confused now than when we spoke before.

I guess we will see what is going on tomorrow.

[SIZEMOREMK]

Oh, the flaky boost gauge just started Wednesday, I wanted to get it unscrewed before I headed your way. I've got a New boost gauge I'm going to install here in a minute.

Sent from my ADR6400L using Tapatalk

[martyo]

Oh, the flaky boost gauge just started Wednesday, I wanted to get it unscrewed before I headed your way. I've got a New boost gauge I'm going to install here in a minute.


Did it settle down after the O ring was replaced?

[SIZEMOREMK]

No, boost needle is getting stuck I think

Sent from my ADR6400L using Tapatalk

[Zack]

I'll give you $8.00

[MOTOWN]

$8.01!!!!!!!!!

[SIZEMOREMK]

Jeff at MO's got me all fixed up! Ended up tweaking the AFR a bit and made some other requested tweaks to the tune.

Not sure if we ever decided if this particular leak was present or how bad it may have been at the time of original tune? My guess is that maybe the o-ring was crooked in there and got sucked into the motor at some point, or it fell in when I removed the injector to inspect.

I've gotten a best of just under 17 MPG for two consecutive tanks when really trying, meaning not going WOT for two whole tanks of gas believe it or not.

In the one tank I've put through it since putting the o-ring in and the re-tune, it got over 17 MPG after quite a few WOT romps and some petty crappy traffic. So I'm going to guess that it had a pretty decent impact on how the car was performing.

[SIZEMOREMK]

It is possible that the O ring came off and I/we forgot to put it on or, it was never there. After all. It was taken on and off more times than I like to remember.

A definite yes on the O2 code. Sounds like a new tune in your future. Or, maybe MartyO can give you some parameters to work/adjust in .

That explains the gradual boost climb. I have never been in another boosted MM so, had nothing to compare it too.

Hey man, I've been meaning to answer the text you sent me a week or so back.

Not to rub it in too much, but I've been enjoying the car very much!

I did probably dog-cuss you and anyone who had ever worked on the car when trying to get the o-ring on the injector, actually the neighboring injector gave me more of a problem because it came off the injector and stayed in the boss when I lifted the rail. My hands are too fat for that kind of thing. Mostly kidding about the dog-cussing part, lol!

This reminded me of the first AOD tranny I tried to build, I unknowingly cut a chunk out of one of the orings on the tail shaft and re-fried the tranny on the first trip to the grocery store:o

As for the boost climb, its hard to say, but it seems to get to 10 psi real quick in 1st and 2nd:D but I don't really trust these boost gauges. I'll be finding a more accurate way to monitor the boost, particularly when I add the additional boost that Jeff at MO's prescribed.


Car is a blast to drive! I got a buddy with a "murdered out" LS3'd GTO and I know he secretly covets my MM:P

Take care man!