Wont Stay Running; Low Compression

[TalonJohn94]

I'll cut to the chase.

I installed a new cylinder head, (new springs and valves - factory cams) including obviously a timing belt job.

After learning I had a bad coil pack I replaced it. But still now the car only starts if you floor the gas. Then it won't hold idle and you can tell it is running rough. Tested spark on all 4 cylinders and I have spark. I know I have fuel to the injectors because the new spark plugs are now dark and smell like fuel.

Which brings me to my question. I did a compression test and they're pretty even across the board at around 65 - 70. Obviously that's low. So how can I determine whether the low compression is due to the cylinder walls having been washed by fuel OR if its valve timing?

 

[VETTE_50_TH]

Run a leak down test. Put the car at TDC, hook a line to one of the spark plug threads, put some air on it, and hear where the leak is. It its from the exhaust or intake, its your valves, if its in the PCV, its the pistons.

 

[TalonJohn94]

Two questions:

Can I use a bike pump?

If its PCV, can I conclude its due to gasoline "wash down"?

 

[VETTE_50_TH]

You might be able to get away with a bike pump and yes that would be because of washing the rings

 

[TalonJohn94]

Ok I definitely think it was just gasoline wash out. So, my valve timing must be off a tooth.

But how does this happen when you have everything lined up and perfect using the VFAQ?

Also, will the valve timing being off by one tooth cause a situation where I have to floor it to start it and it usually won't hold idle?

 

[dyetrying91]

Ok I definitely think it was just gasoline wash out. So, my valve timing must be off a tooth.

But how does this happen when you have everything lined up and perfect using the VFAQ?

Also, will the valve timing being off by one tooth cause a situation where I have to floor it to start it and it usually won't hold idle?

For those kinds of symptoms, it is usually off by more than 1 tooth, or you have a massive vacuum leak somewhere.

 

[steve]

It's very possible you have multiple issues.
Turn the engine over by hand to TDC cylinder 1 and check all the timing marks. Speculating is pointless, just check it. Low numbers like that can easily be due to bad valve timing.

Make sure you didn't break the Engine Coolant Temp sensor wiring, if you have a datalogger check that the ECT matches the IAT input withing a degree or two or each other and the outside temp when the engine is cold or that the values are reasonable if the car has been run.

 

[romeen]

Run a leak down test. Put the car at TDC, hook a line to one of the spark plug threads, put some air on it, and hear where the leak is. It its from the exhaust or intake, its your valves, if its in the PCV, its the pistons.

Agreed.

Two questions:

Can I use a bike pump?

If its PCV, can I conclude its due to gasoline "wash down"?

I highly doubt that would work. Your low compression numbers indicate that you have quite a bit of air leakage so I don't think a bike pump will even come close to keeping the cylinder pressurized.

Keep in mind that you need to have the cams/piston at TDC of the intake stroke for the specific cylinder that you are testing.


Do you know if the lifters were bled before the install?

 

[steve]

Do you know if the lifters were bled before the install?

Good point. If they were pumped up that will effect the compression numbers too.

 

[TalonJohn94]

Ok, I'll try to dig up my Palm Pilot with Pocketlogger.

I can't do it on a "run" but I think I can get it to idle for a while (although for whatever reason the plugs are black and smell of gasoline).

I do wonder if its more than one problem because the car should run and idle being one tooth off from what I've read.

 

[steve]

Ok, I'll try to dig up my Palm Pilot with Pocketlogger.

I can't do it on a "run" but I think I can get it to idle for a while (although for whatever reason the plugs are black and smell of gasoline).

You don't even have to start the car, in fact don't, just turn the ignition on so the ECU is running.

 

[TalonJohn94]

Agreed.





I highly doubt that would work. Your low compression numbers indicate that you have quite a bit of air leakage so I don't think a bike pump will even come close to keeping the cylinder pressurized.

Keep in mind that you need to have the cams/piston at TDC of the intake stroke for the specific cylinder that you are testing.


Do you know if the lifters were bled before the install?

New lifters during cylinder head install

 

[cyclonekid77]

New lifters during cylinder head install

Did you bleed the new lifters or just throw them in?

 

[romeen]

New lifters during cylinder head install

Actually, from my experience brand new lifters need to be bled more than used ones. I couldn't compress my new 3g lifters even the slightest bit before I bled them. Some months later when I removed/reinstalled them they had a little bit of give before bleeding.

As mentioned, if you have access to an air compressor you can use a leak down tester or just a straight air line with adapter fittings to pressurize the cylinders and find out exactly where the air is leaking from.

It may be easier to just go ahead and pull the lifters, bleed them, put them back in. Since you have low compression in all 4 cylinders it's very possible that the lifters are not allowing the valves to close all the way.

 

[2g 6 bolt swap]

Check your timing marks before doing anything else. My car jumped a few teeth randomly and did the same thing you are experiencing. My car would only start with the throttle wide open because it was just dumping fuel into the cylinders. Pull your spark plugs and see if there are wet. If so,your timing is off.

 

[TalonJohn94]

Check your timing marks before doing anything else. My car jumped a few teeth randomly and did the same thing you are experiencing. My car would only start with the throttle wide open because it was just dumping fuel into the cylinders. Pull your spark plugs and see if there are wet. If so,your timing is off.

Just wanted to answer this and update. I did the following quick check:

http://www.dsmtuners.com/forums/art...-1g-2g-quick-timing-belt-alignment-check.html

When the cam gear marks are facing each other and the engine is at TDC, the little notch on the Harmonic Balancer is in line with the "T" on the lower timing belt cover's crankshaft timing mark. So according to this guide, everything should be lined up to assure correct valve timing.

I have to go use my mom's old computer because it has the Palm software and the only computer I know that has a serial port. .... that way I can log the ECU to see if the IAT and ECT sensors are making equal readings.

But to answer this poster: Yes it will only start when I nearly floor it and it then dumps fuel on the spark plugs BUT I just re-installed the cylinder head and therefore lined up the timing belt install perfectly via the VFAQ. Having said that, I know pulling everything back apart to check the valve timing is my next step.

 

[steve]

When the cam gear marks are facing each other and the engine is at TDC, the little notch on the Harmonic Balancer is in line with the "T" on the lower timing belt cover's crankshaft timing mark. So according to this guide, everything should be lined up to assure correct valve timing.

Next step is verifying that the crank pulley mark is really TDC. That involved pulling the spark plug from Cylinder 1 and putting a dowel or screwdriver done the cylinder and making sure it's at TDC with the cam dowels up at the same time that the crank pulley is at the T mark. The rubber holding the inner hub and outer pulley can crack and allow them to shift. If that checks out then you need pull the head or do a leakdown test to find the reason for the low compression.

 

[TalonJohn94]

What's the deal with the bleeding of the NEW lifters?

Actually, from my experience brand new lifters need to be bled more than used ones. I couldn't compress my new 3g lifters even the slightest bit before I bled them.

You were right. I pulled of the valve cover and then continued to pry the rocker arms off and pull out the new lifters. Each one of them was rock hard, unable to compress at all. So I use a small Allen wrench and depressed each one the internal valves within the HLA. I think this might be my problem, and I think I got lucky and didn't bend any valves like HLA "pump up" can [reportedly] do because my compression isn't zero in any of the cylinders.

Anyway, after I bled the HLA's, how the hell do you get them back installed under the cams - the VFAQ just says use a screwdriver but it seems impossible?

(I did have my machinist use +1mm valves - does that mean I won't be able to slip the rocker arms back in?)

 

[TalonJohn94]

Ok, I took all the lifters out and pumped what little oil was in them out and put them back in empty of oil.

The car still wouldn't start.

I did a compression test and my compression numbers improved as follows:

Cylinder #1: 100
Cylinder #2: 80
Cylinder #3: 70
Cylinder #4: 70

Before they were all around 65 - 70. So the lifter thing improved only two cylinders. Could the original (locked up) lifters have caused permanent damage?

The only other thing I can think of is that my machinist sent me back the wrong cams - are there any marking to ensure they are the turbo cams?

 

[TalonJohn94]

What was strange is when I originally put everything together all the cylinders had about 70psi, WITHOUT the internal valve depressed on the new lifters (unable to compress by hand). After I took the lifters back out and pushed the valve in and purged the little bit of oil out I reinstalled. Then, I did a compression test on cylinder 1 - which gave me 100psi. Then I did cylinder 2 - which gave me 80psi. Then I did cylinder number 3 and 4 which both gave me 70psi again.

So it seems that when I did the compression test right after purging the lifters it produced a higher psi in the first cylinder I tested, and diminished in each cylinder after. Does anyone think this could be lifter related?

Does anyone have a leakdown tester I could borrow, in which I would just pay shipping both ways?

 

[TalonJohn94]

Ok, so I did the leakdown test and I had like 30% leakdown.

I called the machinist and he said based on what I have posted and said that I should ship it back for further investigation.

I pulled the head off and did I little inspection. I cant see any major dings or marks on the pistons. I went to pull the valves out to inspect but the valve puller tool I bought broke. (the bolt that pushes on the valve retainer) So now I have to repair the special tool before I can taking the thing apart. I might just skip pulling valves and just send it back to Dale (the machinist) to see what he observes.

I guess the only thing that sucks is shipping costs, replacing brand-new exhaust manifold crush nuts, replacing new head gasket and having to time everything again, etc etc.

Any thoughts?

 

[TalonJohn94]

Update:

I've redone the valve timing, and that yielded:

100, 100, 100, 98

I tried rotating the exhaust cam counterclockwise 1 tooth and that yielded

65, 65, 65, 60

So I returned it back to original as you see here. (And got 100psi across the board) What do you guys think?

Does crank timing mark look right?

 

[TalonJohn94]

Im thinking if all the timing marks are lined up a leakdown test is in order.

Kind of tough w/out an air compressor though.

 

[RLPerformance]

8 months later and no update inbetween? What condition did the head end up being in? Were the vales pressure tested? Curious how the car ran before this head was installed?

 

[TalonJohn94]

The machinist inspected and went through everything and said it tested perfect, and sent it back. I reinstalled with new head gasket (w/ARP's - 85 ft/lbs done in 3 stages, using proper torquing sequence), IM gasket and exhaust mani nuts.

The car ran great with compression as follows (prior to head re-installation):

#1 140
#2 145
#3 145
#4 145

And since I've retimed the thing like 4 times now and the best it can get is 100psi across the board, my next step is another leakdown test. Too bad I don't have a air compressor.

I've also been researching if my lifters could be to blame, but I haven't seen any members here report such a thing. (Topline replacement lifters)

I've thrown out head gasket failure and bad valve lapping because the problem exists across the board