Low compression Problems

[775DSM]

Hey guys im back. Got rid of that 91 TSI problem car and now my buddy gave me a 1990 TSI AWD. The car will run just when you give it more then a little bit of gas it sputters and dies. Did a boost leak no leaks. He said the compression test was around 90 90 100 120. Im told for this car thats bad because this car doesnt even have 100k on it yet. It is a 5 speed and nothing has been done to it. Now i was going to take out plugs and take oil cap off and put a air hose in the plugs and see where air comes out of I.E. Air comes out of exhaust manifold exhaust valves are bad and so on. Now i am leaning towards piston rings. He never looked at the turbo to see if the waste gate housing was toasted like mine was. But i have a feeling that wouldnt cause this it would just cause a lost of boost. Im trying to get some good trouble shooting for this type of problem. The car wont rev very high and like i said it takes it a while to get to 60 if you give it to much gas it sputters and dies. Plugs wires and sensors have been replaced on this car.

 

[95blackGsTurbo]

Those numbers are definitely going to be the majority of the problems. We could help you diagnose what might be helping cause the sputtering but with those numbers its rebuild time. You should really still do the test to see if it is rings or a head problem. Although consistently low numbers like that will usually yield a weak short block. Have you looked into checking the timing? A misaligned timing belt can really throw compression numbers off and just cause all sorts of issues. Even a tooth off. Cars will still run but will have symptoms you described.

 

[jrohner]

There are many things it could be, but low compression probably has nothing to do with it. That compression is not even low enough to notice by how it runs. The first things I would do would be to replace the fuel filter and check to see if the air filter is dirty. The next thing I would probably check would be the ECU (capacitors go bad quite often).

Do you have a data logger of any kind? Is the CEL (check engine light) on?

 

[Honda hunter 1]

There are many things it could be, but low compression probably has nothing to do with it. That compression is not even low enough to notice by how it runs. The first things I would do would be to replace the fuel filter and check to see if the air filter is dirty. The next thing I would probably check would be the ECU (capacitors go bad quite often).

Do you have a data logger of any kind? Is the CEL (check engine light) on?

good idea

 

[95blackGsTurbo]

There are many things it could be, but low compression probably has nothing to do with it. That compression is not even low enough to notice by how it runs. The first things I would do would be to replace the fuel filter and check to see if the air filter is dirty. The next thing I would probably check would be the ECU (capacitors go bad quite often).

Do you have a data logger of any kind? Is the CEL (check engine light) on?

Have you ever driven a car with low compression? A 1g start off with only 7.8:1 and with it losing that much compression it is going to run VERY rich with those low of numbers. You are well below the service limit for a rebuild. Replacing the fuel filter could be the problem but once again DSMers are just recommending he throw parts at it until it fixes the problem. Once you get below the 110-100 mark, on a cold day some cars won't even start. Do you checks first. Check to see where your compression is leaking at. All of your signs point to a misaligned timing belt with the low of a short block mileage. That will also cause a hard start and for it to hesitate under acceleration.

 

[775DSM]

For a problem like this where should i start? Ill take the fuel pump off and blow it out see if its goopy. Then ill do the air test see if im leaking any air out of the exhaust intake or oil cap. From there ill change the spark plugs which are burnt. The only spark plugs i have is the Iridium NGKS (good or bad). But where abouts should i start? Whats a good check list to run down?

 

[95blackGsTurbo]

First I would do those checks. For plugs you will want NGK BPR6ES plugs gaped at .028". Then pull the timing cover and check your marks. Timing Belt VFAQ (Timing Belt TSB - ENHANCED)
Then report back and see what you find. You should probably pulling the timing covers first as it will help you find top dead center as well when doing the air leak check.

 

[775DSM]

Should i find TDC before the air test? Also would anyone happen to know the best cheapest way to get new valves or rings or turbo incase the car does need one? I am looking to get this car to running condition within the next for a new job.

 

[AllWheelRS]

good quick way to check the rings is a wet compression test. One cylinder at a time check the compression, then put about a tablespoon or 2 of oil into the cylinder through the spark plug hole, and test compression on that cylinder again. if compression rises for a few strokes during the wet test you are looking at a bottom end rebuild.

 

[jrohner]

Have you ever driven a car with low compression? A 1g start off with only 7.8:1 and with it losing that much compression it is going to run VERY rich with those low of numbers. You are well below the service limit for a rebuild. Replacing the fuel filter could be the problem but once again DSMers are just recommending he throw parts at it until it fixes the problem. Once you get below the 110-100 mark, on a cold day some cars won't even start. Do you checks first. Check to see where your compression is leaking at. All of your signs point to a misaligned timing belt with the low of a short block mileage. That will also cause a hard start and for it to hesitate under acceleration.

I've driven one with 40-60 on two cylinders and a little over 100 on the other two. It was a little slow at spooling the turbo and a bit doggy off boost (and didn't start very good), but once boost hit it felt just fine.

 

[775DSM]

I dont have a compression tester just a Boost leak tester

 

[river]

The bogging and compression could be misaligned timing, like mentioned before, it could be just a tooth off. Do the timing belt check, and if it's off, fix it. Then when you pull your plugs to do your compression checks, just replace those crap plugs with the NGK BPR6ES's and replace your wires. Also do a fuel filter just because they are cheap. From there if the bogging doesnt improve, you may be overrunning your injectors. Long story short though, if your timing is dead on, be prepared to overhaul the engine...new rings, bottom end bearings, head gasket, and have the head gone through...new valve guides, seals, valves, decked, hot tanked, etc.

 

[95blackGsTurbo]

Yes you have to find TDC before the air test on each cylinder that way the valves are closed otherwise your just going to lose it all through the exhaust or intake.

 

[MidShipCivic]

There are many things it could be, but low compression probably has nothing to do with it. That compression is not even low enough to notice by how it runs. The first things I would do would be to replace the fuel filter and check to see if the air filter is dirty. The next thing I would probably check would be the ECU (capacitors go bad quite often).

Incorrect. If you have a 150 psi (normal compression for 1g) and 90 psi all four cylinders.

You will notice an immediate sound difference on top of that the engine will not combust the mixture correctly leaving fuel in the cylinder thinning out the gas since it will seep past the rings more often.

I've driven one with 40-60 on two cylinders and a little over 100 on the other two. It was a little slow at spooling the turbo and a bit doggy off boost (and didn't start very good), but once boost hit it felt just fine.

This doesn't justify having low compression.

 

[775DSM]

Turbo is off and is complete trashed the play in it is ridicilous and oil pored out of the intercooler line. Now i am still going to check timing and Leak down test it still. I drove it 100 miles today and the car only bogs when the turbo meter hits 0 and turbo attempts to boost. If i keep my foot off the gas and just cruise with barley any gas it runs fine idles fine as well. Im thinking most of my problems are coming from the turbo. ANYONE KNOW WHERE I CAN GET A FACTORY FOR CHEAP????

 

[MidShipCivic]

Turbo is off and is complete trashed the play in it is ridicilous and oil pored out of the intercooler line. Now i am still going to check timing and Leak down test it still. I drove it 100 miles today and the car only bogs when the turbo meter hits 0 and turbo attempts to boost. If i keep my foot off the gas and just cruise with barley any gas it runs fine idles fine as well. Im thinking most of my problems are coming from the turbo. ANYONE KNOW WHERE I CAN GET A FACTORY FOR CHEAP????

Factory ?

You should at least replace those rings, your performance is going to suffer and while it's out you can remove other failure prone items.

 

[775DSM]

Yes but im looking for another 16G turbo now while i have the money. Whats the difficulty on rebuilding one? Rebuild kits are around 60$ and a new Big EVO 16G is around 200. I am today doing the head gasket intake manifold gasket valve cover gasket and leak down test. I pulled the turbo last night.

 

[95blackGsTurbo]

I would either strap on a good used 14b or 16g or save money for a quality new unit. You won't find a known reliable 16g new for $200. Your taking a chance with those knock off ones. PM DSM Forums - View Profile: jusmx141 and see what he has or will charge.

 

[Alex Bland]

just a weird question i stoped by some guys house the other day to look at his 1g and he said "its all stock" and poped the hook and it was but he wanted the psssh sound so he put a aftermarket BOV on it. just making sure u wernt doing the same thing, also if he said thats the numbers i would dubble check it urself

oh and also i rebuilt a 14b turbo and was scared so bad was my first rebuild on anything and it was super easy to do

 

[775DSM]

ok the heads off. Coolant was sitting on the head gasket, im taking the head to get machined and the piston walls look fine there is build up on the pistons. The valves look burnt there are a rust color. I did a leak down test no air out of any where. Vacuum lines are spliced and capped just about every where. I am replacing every gasket i humanly can on this car. The BOV is not vented it is being recirculated. I dont know what else i should look into. I have this car apart and not to sure what to replace. There is like a bunch of gasket like material over the valve cover the Thermostat housing. Should i get the block shaved or should i just use some light sand paper to get off the old head gasket? Also are the valves fine if they are a rust color? But like i said no air leak out of any of it. I did find coolant on the head gasket tho. How could i tell if the rings are bad from here without taking the crank out? Also the timing looked off. The bottom left sprocket to the right of the crank was off its needle the dot on the sprocket did not line up with the needle but everything else did. All belts look fine so do the injectors. Fuel filter is not clogged.

I am looking for more suggestions to go over from here. I am very strapped for cash so keep the ideas cheap.

 

[river]

When I do head swaps or headgasket changes and I know nothing is warped, I just take a razor blade to the block, then when it's cleaned off I take brake cleaner and clean the surface. For the head I do the same thing, a straight razor and then brake cleaner to clean the surface. The head is aluminum though, so be careful not to gouge the razor into the head. Doing it this way you have to be careful to not get gasket residue into oil or coolant galleys, or combustion chambers. Take your time and do it well. Then I copper spray the hell out of my head gasket. I generally use either the OEM Mitsu HG or I've had very good luck with the Fel-Pro HG. Either way, copper spray either of them. Another good thing to invest in is re-usable head studs, ARP to be specific. In order to get the head on/off without pulling the motor mount you need to trim the dog ear off....follow this link... http://www.vfaq.com/mods/headstuds.html Also, if you do the ARP's...make sure to set the washers in the head BEFORE you set the head on.

It sounds like you have problems with the piston rings themselves...so you need to get your shortblock rebuilt.

If your turbo is trashed as well, then you need to get a new turbo as well...or a rebuild. If you chance your luck with an EBAY turbo, ok...but if you're strapped for cash you may want to do it right and get a genuine REAL evo III or whatever turbo you choose.

 

[775DSM]

today i have pulled the Cat and am going to hammer it out and then drop my muffler. I did a leak down test and nothing leaks. I did how ever find out the timing was off the balance / oil pump sprocket. So i am going to get my head done friday and put it back on later friday afternoon after cleaning the block. I will then reblance the timing to spec and put the old turbo back on after cleaning it out. I will see how it goes from there. The valves / rings registered fine in the leak pressure test. Dang this is almost turning into a build topic. But any more suggestion would be GREAT and thank you so far for the heads up guys

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OK so cat was completely clogged the head was U'd in the middle and was 10,000's off and maxim is 2,000. Valves show some signs of wearing but no leaks. I am putting the car back together today and hoping to see some improvement as far as it running. If not then next weekend i am going to pull the crank shaft do the bearings and seals and rings.

 

[Honda hunter 1]

today i have pulled the Cat and am going to hammer it out and then drop my muffler. I did a leak down test and nothing leaks. I did how ever find out the timing was off the balance / oil pump sprocket. So i am going to get my head done friday and put it back on later friday afternoon after cleaning the block. I will then reblance the timing to spec and put the old turbo back on after cleaning it out. I will see how it goes from there. The valves / rings registered fine in the leak pressure test. Dang this is almost turning into a build topic. But any more suggestion would be GREAT and thank you so far for the heads up guys

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OK so cat was completely clogged the head was U'd in the middle and was 10,000's off and maxim is 2,000. Valves show some signs of wearing but no leaks. I am putting the car back together today and hoping to see some improvement as far as it running. If not then next weekend i am going to pull the crank shaft do the bearings and seals and rings.

good luck whit the car

 

[frankenstein406]

Might as well clean the carbon out of the exhaust ports well its off. Is mani cracked from cat being clogged?

 

[SrKegler]

Guys, that post is from a year and a half ago. Probably got it fixed by now.