RRT vette

I'm starting all over here. I found my vac leak and fixed. I went out just now and followed procedure for minimal idle. I disconnected the EST, grounded ALDL and disconnected new IAC. Started engine and ran Field Service Mode and in open loop the SES light flashes 3 x sec (rich). Engine warmed up to 180* Field Service Mode, SES light flashes once/sec (normal) and I set minimal idle and adjusted TPS to .59v in Drive. I checked timing and set at 8* BTDC. Stopped engine and connected IAC and EST. Started engine again and ran good. My RPM guage doesn't work but sounded to be between 400-600 RPM's idle. Field Service Mode light flashes once/sec. The engine sounds smooth but shakes a bit and exhaust smell rich. Double checked everything, fuel pressure at 42 psi and unplugged FPR vac and pressure goes to 46psi. Stopped engine and counted my fuel pressure drop. Injectors are Accel 24 lb and about 3 months old. Previous owner had chip tuned for timing and the engine is stock except for exhaust system. No headers

Engine off: 42 psi
1 min: 41 psi
2 min: 40 psi
3 min: 36 psi
4 min: 36 psi
5 min: 32 psi
6 min: 30 psi
7 min: 26 psi
8 min: 26 psi
9 min: 21 psi
10 min: 20 psi

Any suggestions?

JBB

Is the return line closed on that leak down test?

RRT vette

No, this is the leak down while watching my guage.

RRT vette

I pulled my plugs and all are black except for #5 and #7 are black with white tip, I replaced them. I took it for a drive and now I have a poping noise coming from the TB at a low RPM range 1500-2000. Still rich.

RRT vette

bump

JBB

Your symptoms are Smells rich & pops through the intake? Is the pop only on acceleration?

First make sure 5+7 plug wires aren't reversed. (It happens)
Has it been popping awhile, or just after recent repairs?
Any codes?

RRT vette

I'll check and make sure of the plug wire. It started popping after a recent minimal idle and tps adjustment (checked out fine). No codes. Yes, the popping is on acceleraton at about 1,500 to 2,000 RPMs only.
Thanks

rick lambert

One thing I just don't get..where is 22 lbs of pressure going in 10 minutes. Mine dropped about 5 or 6 and held for a half hour, that's when I said good enough and disconnected.

RRT vette

Well the only thing I can think of at this point is leaky injector(s) which are new, leaky CSV, or leaky check valve. The FPR doen't show any signs of gas in the vacuum and I don't see/smell any raw gas. I will pinch off the return line first and then the feed line and see what difference it makes. The engine starts a split second quicker hot than it does cold, so that should tell me the injectors are o.k. and not leaking. I guess I need to cut my losses and get a newer vette. Just kidding.

AKS Racing

In order of frequency, I have found failures causing leakdown:
1) injectors
2) regulator
3) fuel pump / check valve

And have yet to find a ruptured diaphragm causing fuel to leak into the manifold.

On one of my personal cars, I recently had a failed aftermarket regulator causing fuel to drain back to the tank after shutdown in about 2 mins. The real problem is refilling all of the lines with just the 6 sec pulse when you go to restart. This is a real pain, as sometimes it would take 6 tries before you get enough fuel to start (and rememeber that each time requires ~60 sec reset time).

Aaron

rick lambert

since he has not seen signs of fuel at the FPR, and the injectors are new, I'd suspect the FP check valve. That can wait though. I also think his rich smell is do to the CTS.

RRT vette

Possible the check valve or cold start valve. Only way I know of to rule out CSV is to plug the hose to the fuel rail to rule out. Even if I disconnect the CSV harness it will still have fuel pressure and could leak. It ohmed around 4-5 ohms which I was told is normal for this injector. I have plans to replace the CTS and check shut down pressure with fuel return line pinched and then prime and check shut down pressure with fuel feed line pinched. It is leaking down a little quicker than I would like but it's not a sudden drop...it's like a small leak if any. I will do this when I can get a day off work. I plan on replacing the CTS and a different ECM for the rich condition.

If any other suggestions I'm all

RRT vette

UPDATE:

I ohmed the CTS and it check out O.K. So my rich problem is elsewhere. I called the fellow that had it before me and am waiting for a call back. I keep everyone posted.

RRT vette

Just checked fuel pressure drop. Results below. I removed the gas lid and rubber filler. My guage is connected and I turn the key on and pressure settles on 40 and pinched off fuel return line...same for fuel feed line test. And yes, I know which line is which. The test in the first post was no lines pinched just watching guage.

Return Line:
Start: 40 psi
1 min: 40 psi
2 min: 39 psi
3 min: 38 psi
4 min: 37 psi
5 min: 36 psi
6 min: 36 psi
7 min: 35 psi
8 min: 35 psi
9 min: 35 psi
10 min: 34 psi

Feed Line:
Start: 40psi ......Pinch feed line it goes to 44 psi
1 min: 43 psi
2 min: 43 psi
3 min: 42 psi
4 min: 41 psi
5 min: 40 psi
6 min: 39 psi
7 min: 38 psi
8 min: 37 psi
9 min: 36 psi
10 min 35 psi

rick lambert

my bets on the check valve.

RRT vette

It probably is the check valve. I just had the fuel pump out about 3 months ago and replaced it with AC Delco. The small leak is not affecting my start times and I don't think leaky injectors would let it start fast when hot. Fuel pressure is normal idle and drive, I had a concern with the 24 lbs on a stock motor but everyone here seems to think its fine. The CTS ohmed at 2,200 ohms at 85*f, so that was good. This is a good one, I'll switch out the ECM's and see what happens next.

rick lambert

You can obviously see the difference...it holds much better. I wouldn't be to concerned about it until you find the rich problem, it's obviously eliminated any leaky injector(s). The ECM may do the trick. Good luck

tequilaboy

You have larger injectors than stock and you're running rich. Hmmm....

Has any chip tuning been done to compensate for the bigger injectors? You could reduce your fuel pressure to get the flow rate back in the ball park. Try a 5-10% reduction in fuel pressure.

RRT vette

Yes, at least I now it will be easier to access the check valve that pulling the injectors.

rick lambert

That's part of the unknown equation, he has a custom chip, from a previous owner...that's why he's trying another chip/ECM.I haven't heard anyone haveing problems with 24#.