1G 91 Talon can low compression cause this?

[New2tuning]

I have a 91 Talon TSi witht he following mods.
Evo III 16g
1990 TB
FMIC
Type S BOV
550s
2G MAF
2G TB elbow
SAFC
AFPR
Walbro 255
Full 3" exhaust (no cat)
Some other stuff but nothing that would affect engine things I dont think.

I started to get idle surge one day and by the end of the day my car was bucking real hard (like fuel cut) but wasnt blowing black smoke. I did a boots leak test and the system wont hold any amount of PSI, I can hear it going into (and I assume out of) the valve cover. I did a compression test and came up with the following numbers

Dry/Wet

145/150 125/135 145/150 145/150

Would my low compression cause idle surge and the bucking I am feeling? I redid all the gaskets on my TB and elbow and when I leak check the FMIC piping it holds solid.

 

[leakyfaucet]

No- low compression won't cause idle surge or bucking. However, a very large boost leak can. Your compression isn't that bad, really.

 

[jasteel13]

if you cant hold any pressure while doing the boost leak test you have a bad leak somewhere... maybe your intake manifold gasket? if it is by the valve cover

 

[dsm-onster]

I started to get idle surge one day and by the end of the day my car was bucking real hard (like fuel cut) but wasnt blowing black smoke. I did a boots leak test and the system wont hold any amount of PSI, I can hear it going into (and I assume out of) the valve cover. I did a compression test and came up with the following numbers

Dry/Wet

145/150 125/135 145/150 145/150

It is highly likely that you have a blown out intake manifold gasket. This exact same scenerio occured with me.

 

[compression]

you could also check your shaft seals in the tb. ecspecially if you just put it on it could have been bad before you put it on. just my $0.02

 

[New2tuning]

I soaked down the TB when doing the test and the seals didnt seem to leak but I had a small leak from the BISS. I replaced the oring and tightened it back down and it doesnt leak now. The guy that had the car before me blew the intake mani gasket before and maybe it wasnt put back on correctly. I will check that and let all know if it fixed it in case someone needs this info in a future search.

 

[Reese92tsi]

Looks like you'll be replacing a head gasket soon .

 

[importboost]

Looks like you'll be replacing a head gasket soon .

Why would he do that Nogg?(sp) Compression was fine????

 

[Reese92tsi]

Why would he do that Nogg?(sp) Compression was fine????

About a month ago we performed a compression test in class and we were seeing 150-160s across the board so between then and now he must have done sumthin he ain't had no business doing . Differences between his wet & dry tests rule out rings and the numbers are way to high to indicate burnt/bent/warped valves so the only other possibility would be a leaky headgasket.

btw the names Maurice Lawrence NOCK

 

[New2tuning]

I ordered this today
http://www.slowboyracing.com/more.php?id=5257&
Hopefully I get in and get the car back together before we start back at school.
Intake mani doesn't affect compression only head gasket, rings, and valves. You better tell Earl to go back over some of last semester with you bro hehe j/k

 

[Reese92tsi]

I ordered this today
http://www.slowboyracing.com/more.php?id=5257&
Hopefully I get in and get the car back together before we start back at school.
Intake mani doesn't affect compression only head gasket, rings, and valves. You better tell Earl to go back over some of last semester with you bro hehe j/k

Did I say an Intake mani will affect your compression??? ???
Looks like you need a reading comprehension class J/K

 

[itwillgo]

About the head gasket issue I had done multiple compression checks on mine but was contiually blowing coolant but the compression was good 150+ all the way across and finally gave up on everything else and pulled the head to find the gasket gone on #2 cylinder so compresion check will not always show a leak. Got to remember the boost we are putting in that engine.

 

[New2tuning]

Yeah Im a retard, I thought you said intake gasket not head gasket. The headgasket should be good for awhile, we had one low cylinder in class too.

 

[Reese92tsi]

Its all good bro, hopefully the IM gasket is the cause of your bucking instead of something internal.

 

[sp00ln]

I hope you dont mind me butting in,

I did a leak test the other day to check up on things. I set it to TDC and got my soapy water out. I did the leak test and I found no leaks around any of the IC pipes/bov/couplers, but there was slight one on the TB where the seals are... I'll let that one go. However, my question is how long should the pressure hold? Mine dies off down to ~4psi if you stop putting air into it. I also discovered if you take off my oil cap and listen you can hear air in the head. Is that normal? Nothing is bubbling or anything, but you can just hear the air filling into there. And the car runs strong. Any thoughts?

Thanks.