2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Is my engine blown? Compression test vid inside

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Old Oct 22, 2008 | 05:00 PM
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Is my engine blown? Compression test vid inside

Compression seems to be 92 psi x3 F and 80psi x3 (?) R. There is some white smoke when the car is revved but it did sit for 3 months.

How it runs:




Story: Started the car up (just finished 6 port turbo), ran GREAT with a smooth idle, no hesitations, etc. Went for a drive, WOT redlined it (bad idea, I know), boosted hard and an intercooler pipe blew off Torqued the clamp down, started it up again and it is now misfiring, hesitating and bucking all over the place. The car drives but is stumbling and hesitating...still boosts hard but hits fuel cut or something and bogs intermittently...runs like CRAP. I changed out the leading plugs to known good (eh) ones, coils good, wires are good. It has good torque so its not running on one rotor (I know what that feels like)...more like one and a half.

I have no idea wtf could've happened when I drove it. It couldn't have gone over 8.6psi cause thats fuel cut. The timing is dead on. Best case scenario its leaky injectors, since they were bought used. I'd like some input before I drop another engine in. Edit: And when I drove the car (running crappy) and redlined it it pulled hard and left a CLOWD of black smoke behind.

Thanks.

Last edited by KhanArtisT; Oct 22, 2008 at 05:03 PM. Reason: More info:
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Old Oct 22, 2008 | 05:18 PM
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You really need to let the motor break in before you drive it hard like that if it's a new motor. That being said, for a fresh rebuild, your compression numbers aren't great but it could just need run time to build compression.

From how it's running it could be running stupid rich. Check to make sure the vaccume line didn't blow off the MAP sensor and check to make sure the MAF isn't stuck open.
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Old Oct 22, 2008 | 05:29 PM
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Its actually an old Kevin Landers rebuild with ~60k hard miles on it. Ran great before it was boosted. For a 6 port engine with 9.7:1 compression the numbers are very low. Just not sure if thats the reason its running like ****, it feels like its running rich, burns a whole gallon of fuel just idling and driving not even 1/4 mile.

Vac line for MAP is good, MAF is good also. The car is running open 2.5" downpipe with no O2 btw.
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Old Oct 22, 2008 | 05:29 PM
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put brand new plugs in there and pressure test for boost leaks.
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Old Oct 22, 2008 | 07:01 PM
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doesnt sound very promising for you man...
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Old Oct 22, 2008 | 07:19 PM
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Originally Posted by arghx
put brand new plugs in there and pressure test for boost leaks.
+1

Check thoroughly for intake leaks and broken/disconnected afm wires. From the videos you provided, I feel secure in saying your engine is not blown.
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Old Oct 22, 2008 | 07:37 PM
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Get an aftermarket computer.... That is a start.

If your a diy guy you can have a microtech installed for under 950.
Compression looks fine to me.

Last edited by rx72c; Oct 22, 2008 at 07:40 PM.
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Old Oct 22, 2008 | 07:42 PM
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Originally Posted by arghx
put brand new plugs in there and pressure test for boost leaks.
I might actually do this, the plugs have like 200 miles on them but may have been fouled when the car was flooded to hell when I was troubleshooting the injectors.

But the car isn't stumbling and dying now...it was almost out of gas, lol. It drives OK but hesitates like crazy and boost randomly hits after like 5k and after that it pulls hard, no smoke anymore either. I will post a driving vid either tonight or tomorrow, thanks for all the help so far.
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Old Oct 23, 2008 | 03:12 PM
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So I just found the problem: timing. I removed the CAS and spun the gear to listen for plugs and injectors firing and then put it back in very roughly adjusted. Started the car up and it runs completely normal now. If I bring the yellow 5* TDC mark towards the pointer while the engine is running w/ the timing light it starts to run like **** again. When it is more towards the passenger side it runs normal. I'm stumped...because at first it was dead on and it ran fine when it was initially started...did the ECU detect knock and retard the timing to get the car into limp mode? I see a sensor that screws into a housing with 1 wire going to it, but I didn't think the NA cars had knock sensors..I'm going to take it for a spin and see how it runs.
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Old Oct 23, 2008 | 03:25 PM
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Originally Posted by Anti-trust7
doesnt sound very promising for you man...
what kind of post was this, are u trying to boost up your post count....

anywasy bro i got that engine lalalalalalalalal
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Old Oct 23, 2008 | 03:54 PM
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I don't recall knock sensors on NAs either. You can easily check the FSM, it should be in there.
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Old Oct 23, 2008 | 04:25 PM
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I just went for a spin and the car runs great. Scrap all the timing crap cause I think I was adjusting timing with it at like 1500rpm since thats the only speed it would be smooth at. Very smooth idle, great startup and pulls smoothly, just won't make any boost. It doesn't even really pull until 5k. Its probably making like 2 psi because it pulls way harder than before. Might cap my wastegate line and go for an easy drive, I also might have my boost gauge line on a nipple that doesn't see pressure. This thing is like a never ending project!

And the sensor is not on the housing its under the heater hose so its probably coolant temp. I also have octane booster in it with 1/4 tank 93 just in case. Edit: Oh and the rear rotor's trailing wire was pulled off the coil too

Last edited by KhanArtisT; Oct 23, 2008 at 04:33 PM.
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Old Oct 23, 2008 | 09:25 PM
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imma bet you have the boost gauge on a vacuum only nipple , and btw what ecu are you running ?
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Old Oct 23, 2008 | 10:16 PM
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Its running the stock TII ECU with the sensors. How exactly do I know which nipple sees pressure and which doesn't? I think I'm going to tee into the vacuum line for the MAP...
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Old Oct 23, 2008 | 10:30 PM
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Once the car's running, unplugging a line would immediately introduce a vacuum leak, thus letting you know which one sees pressure.
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Old Oct 25, 2008 | 09:41 PM
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So the problem was a crappy boost gauge and my wastegate opening too early. My entire secondary arm setup was crap because the wastegate arm can move up/down and side/side. I redid it and mounted the wastegate to the frame with a wire attaching it to the flapper and it works great.

Boosting 5 psi now and it pulls hard as fawk
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