SR20DET rebuilt head, valve job, stuck injector, wierd leakdown

[pizzaman]

Alright i'll try to be concise. Basically my frame gave out a few years back and I finally found a empty chassis. Did a frame swap and pulled the motor, ran a compression test and the results were 170s across the board so I figured the bottom end was solid. When I removed the head the valve guides were bad and burning a little oil, whoopty doo. Got a head job new valve guides and valve job, and HG. Put everything together it ran fine and dandy. About 20 miles later one day I wake up and start the car and I smell gas in the driver seat and white smoke coming out the tail pipe, also noticed gas leaking from around the exhaust manifold, so I shut the car off and figured it was a faulty injector. Grad school has recently started so I did not have the time/patience to deal with the piece so I had it towed to the nearest shop and told them that I believe it's a faulty injector and to just replace it.

Here is where things get a little dicey, the shop calls me and tells me they want to do a boost leak test and a leakdown test to make sure there are not any other issues so I agree. They call me back and confirm a injector stuck open and gave my leakdown results as follows:

#1 91%
#2 40%
#3 86%
#4 30%

Now the mechanic said that he wants to pull the head and check out the timing and valves and whatnot to which I responded with my whole backstory. Now he performed the leakdown test on the car cold. So is it possible that if there was gas in the cylinder on a cold engine leakdown numbers would not be accurate? I told him to first change out the injector, spark plugs and the oil and redo the test, but in the case that my bottom end has shot ring landings or the cylinder walls are fuel washed what other options do I have?

Currently my engine specs are pretty stock: SR20DET redtop, S15 turbo, tomei fuel pump on a stock FPR (which i think might have caused the faulty injector), FMIC, downpipe, exhaust, nothing too fancy.

They said they will change out the plugs, injector, and oil and redo the test but worst case scenario what are my options?

[Rayne]

Get a stock fuel pump or up grade your fuel pressure regulator.

[kleenS14]

Those leak down results are pretty suspect. It's extremely difficult to have 90%. I mean, that's like a broken valve spring or a hole in the piston. Id make sure they are doing the test correctly and their gauge is accurate. With those numbers, you'd be missing in every cylinder. With that said, your fuel setup has nothing to do with a stuck injector. It just happens sometimes. If you put the tip of a screwdriver on the injectors you'll be able to hear each one individually closing, or not closing. Sounds like a ticking noise. With a stuck injector you can wash out cylinder walls and reduce your compression, but it's basically impossible to make it a 90% leak, short of bending a rod due to hydro lock (very difficult to do). Id re evaluate it from the beginning, or take it to another shop. Just my 2 cents.

[pacotaco345]

Those leak down results are pretty suspect. It's extremely difficult to have 90%. I mean, that's like a broken valve spring or a hole in the piston. Id make sure they are doing the test correctly and their gauge is accurate. With those numbers, you'd be missing in every cylinder. With that said, your fuel setup has nothing to do with a stuck injector. It just happens sometimes. If you put the tip of a screwdriver on the injectors you'll be able to hear each one individually closing, or not closing. Sounds like a ticking noise. With a stuck injector you can wash out cylinder walls and reduce your compression, but it's basically impossible to make it a 90% leak, short of bending a rod due to hydro lock (very difficult to do). Id re evaluate it from the beginning, or take it to another shop. Just my 2 cents.

I'm pretty sure the 90% was only leaking 10% of the air not the way you are interpreting it... OP regarding what to do, have the shop perform the maintenance you suggested and start the car, perform compression test while its warm. Make sure you're there or do it yourself so you know they aren't just trying to get money out of you. If its still bad then you need to go through the bottom end and at least run a hone through the cylinders.

[pizzaman]

For an update, they performed the maintenance and redid the test and the cylinders were all within the upper 80s/low 90s. I just think it is strange that the shop I went to wanted to do all these other things when I told them that I believe there was a injector wide open. Sort of like they were giving me the ol'reach-around. What I learned though was that doing a leak down test on a car not in optimal condition will yield bad results.

Also, KleenS14, I recently just moved to the Ashburn area of NoVa and the shop I took it to was ptuning in Manassas, do you know of a better shop to go to when I need to have my car worked on?

[kleenS14]

Honestly, don't know much about p tuning. Heard of them forever, beautiful shop but don't know anything they've done. More if a Honda shop from my knowledge. Don't know any of the guys they have working there, but I've worked in a lot of shops in the area from aam to funktion tuned. Known a lot of people in the area for a long time. I'd volunteer to take a look at it but I'm out in wv right now, bout an hour from Ashburn. The guys at moore automotive in Fairfax are pretty cool. I've dealt with them before for quite a few tunes and they're tuner/main tech Chris is very straight forward and they've dealt with a ton of sr20s. The only problem is their lead time to get in....good for them they're always busy lol. Otherwise not really, the market is pretty thin, our cars are old and thats a horribly rich area lol. You want Porsche or lambo shop I know of many. Dudes in socal think there's money out there....:).

But getting back to your issue the test conditions shouldn't matter much for a leak down. Compression tests are shit, leak down will give better data still warm with fresh oil in the cylinder walls/rings but there's no such thing as bad data. I test motors dead cold and don't ever get scary results. Remember a leak down relies on hg integrity, rings as well as valves seating in the head. 90% on a leak down is impossible to interpret differently, the gauge simply doesn't read that way. Hope you're end result was satisfactory. My cylinder head just shat valves all over my piston and turbine wheel....just to help you feel better about your situation ;) haha. Best of luck, and if you need any help feel free to pm me.