Wierd boost or fuel issue...???

[ronsam2006]

Ok guys, I have a 1992 TSI fwd. It has been running great up until the past few months. It is really hard to explain..but here goes. It has basic everything and is in the high 2XX whp range and low 3XX torque on a Evo 3 16G.

I was driving one day and cruising at 70 mph on the hwy at around 3000 rpm. Everything is fine...and all of a sudden it started shuddering...under like 10-20 percent throttle. This happened several months ago and hasn't stopped since. I cannot detect that this is a change due to weather or not. Slight shudders, but then all of sudden it would stop or go on like that for miles. Now...that being said...

Here is another problem which I think is linked to the problem above...
This problem happens only sometimes as well...Im cruising at like 3500 rpm or whatever in suppose 2nd or 3 gear...then I floor it and all it does is give a couple seconds lag(barely any boost is building)...then all of a sudden, black smoke(fuel) along with a anti-lag noise, seriously ANTI-LAG noise comes for a couple seconds then hits boost normally like it should. Mind you, this is all happening while my foot is floored to the gas pedal.

I haven't done anything to my car that would make it act this way as far as I can think....the only thing I can think of is that my stock HG is cracked. I have been running on a cracked HG for a while...is that getting worse...But I have never heard of a cracked HG causing such problems ON AND OFF...??? The second problem seems like its having a hard time transitioning from low throttle to high throttle....because my low throttle settings on my AFC are stock(550cc injecttors) and high throttle is a little bit of negative then positive in the 3400rpm and up. Any ideas....? Any help is highly appreciated.

 

[ronsam2006]

I just finished my profile...so my car stats are also updated.

 

[pj91gsx]

When you say head gasket do you actually mean the gasket between the block and head is cracked? How would you know? I have a friend that will gasket any gasket on the head a head gasket, so Im just checking. I think you should do a compression test to make sure the head gasket is not the issue. You should do a boost leak test if the head gasket is not the issue.

Some people had problems with the greddy type s leaking boost. If you havent done I boost leak test I would recommend you do one.

 

[ronsam2006]

When you say head gasket do you actually mean the gasket between the block and head is cracked? How would you know? I have a friend that will gasket any gasket on the head a head gasket, so Im just checking. I think you should do a compression test to make sure the head gasket is not the issue. You should do a boost leak test if the head gasket is not the issue.

Some people had problems with the greddy type s leaking boost. If you havent done I boost leak test I would recommend you do one.

Oh its definitely the head gasket between the head and block. I got a block check done like 4 to 5 months ago at a radiator shop...they said it wasn't the hg. But now im dead sure it is. When I was getting it dyno tuned a couple months ago, while doing a dyno pull....after 5500rpm, coolant would shoot out with pressure from the coolant reservoir dump tube. Plus the reservoir smells like exhaust gases. I haven't done a compression test, but we did a leak down test a few months ago, and it was like this...cylinder 1(closest to timing belt) was 22% leak, 2 was 28%, 3 was 32% and 4 was 13%. They say a good motor is between 5-10% leak. It could be the rings as well. Maybe I should do a compression test. Also, I have to refill on coolant every 4-5 days.

 

[ronsam2006]

anyone???

 

[stefanOst]

How did that compression test check out?

 

[Jeff99GS]

Have you checked the spark plugs? its very easy to do and its a good way to see WHAT is going on INSIDE the motor. If they are Black and covered with soot, then you are TOO rich...If they are bright white...then you are too lean....I would replace the plugs or at least re-Gap them....It almost sounds like you're too rich on your low settings and its blowing out your spark.

 

[ronsam2006]

Have you checked the spark plugs? its very easy to do and its a good way to see WHAT is going on INSIDE the motor. If they are Black and covered with soot, then you are TOO rich...If they are bright white...then you are too lean....I would replace the plugs or at least re-Gap them....It almost sounds like you're too rich on your low settings and its blowing out your spark.

I am tuned....I replace plugs every 3k miles and even after I did this, it was still shuddering. They are also properly gapped to .028(bpr7es comes factory gapped to .028). I am thinking they are the plug wires.

 

[pj91gsx]

Also, I have to refill on coolant every 4-5 days.

This is definitely not normal. You are leaking coolant somewhere. Check your dipstick and see if its white. See if you exhaust is smoking white. Do a compression test as well. I dont now exactly what a leak down test is but i thought it doesnt have anything to do with piston rings. What is a leak down test? How is it done?

 

[ronsam2006]

I do see exhaust smoke from my tail pipe from time to time. The coolant doesn't dissapear, every time I do a hard pull through a couple of gears, coolant is forced out of the dump tube because exhaust gases are escaping into the coolant chambers and forcing it out. So the coolant keeps being pushed to the ground. I have gone without having to fill coolant for two weeks because I never did a hard pull throughout those two weeks.
A leak down test is done almost the same way as a compression test...but I think leak down gives you the condition of the head gasket as well. Plus you dont have to crank it to do it. So you screw in a guage to the spark plus thread that is attached to an air compressor...then you make sure the cylinder that it is connected to is at the top dead center...then you let the air rip...and it gives you a reading of how much percentage the air is holding...subtract that by a 100% and you have the air that is escaping. I am not sure of how much air or the guage you use...but thats basically it. My tuner did it before he threw it on the dyno so he would know the condition of my engine. Good thing he did it because it was pretty bad.

But back to the main problem...does anyone know what I am talking about??? My friend who has a 1Gb also is having the same problem and we can't figure out whats going on....

 

[indy1g]

Before you worry about the hesitation and backfire, Why dont you worry about the blown headgasket? That in itsself could be causing the problem.

The fact that you continue running it with a blown headgasket is just asking for a warped head or a blown engine. Id bet a million that your oil is like water and looks like milk.

Fix the big before you consider the small man. Your car will only treat you as good as you treat it.

 

[ronsam2006]

Just did a compression test....results go like this

cylinder 1 closest to the timing belt - 150
cylinder 2 - 147
cylinder 3 - 150
cylinder 4 - 145

 

[Jeff99GS]

Those numbers don't sound too bad to me...seems like normal for a 1g with higher milage

I dont think your headgasket is bad.

 

[ronsam2006]

Those numbers don't sound too bad to me...seems like normal for a 1g with higher milage

I dont think your headgasket is bad.

Well if it isnt a HG...then what is causing coolant to spew out like that every time i push it?

 

[Jeff99GS]

Well if it isnt a HG...then what is causing coolant to spew out like that every time i push it?

The only reason I dont think it's the HG is cause of the Compression Numbers you posted.

You said earlier that the coolant is coming out of your overflow bottle...so the first thing I would do is replace the Coolant System Cap (radiator cap)
When those go bad they do NOT hold in the proper pressure of the cooling system. It allows coolant to escape into the overflow bottle... once that fills up it overflows to the ground.

I would try the easy stuff first... go buy a new Radiator Cap for $5 and get a new Thermostat and t-stat housing gasket $15 and check all of you coolant hoses for leaks.