Topic: Some engine issues- Need help

[sharpxmen]

That's more like what I need...  I have been trying to figure out how to use the leak down tester's hose for the compression test, but I cant figure out how to install a valve on that one...

i'm thinking that could be too long for cyl 1 and possibly 2 since you have the A/C compressor there.

try to wrap some electrical take around the fitting on the compressor so it will keep it centered in the spark plug hole (just how the socked does when you install the plugs) - i remember having to fiddle that fitting a bit to get it right on the thread so this could help.

[jfrabat]

I am still trying to see if I can use the leak down tester hose instead...  By the way, here's a pic I managed to get of the compression tester trying to reach the threads on the plug hole, as well as a comparisson with the leak down tester:





Felipe

[aw12345]

what's the hex size on the compression tester fitting, that migt bottom out in the plug holes before getting to the thread, there is usually an extender you can use in that case.



1 & 2 look normal, not sure why 3 & 4 have nothing on, were they wet?

Looking at the plugs I doubt that a serious lack of compression is your problem.
They all have good combustion. Have you tried the easiest thing of all a plain ole vacuum gauge? It tells quite a bit about engine condition with very little work.
Cylinder contribution is not a bad test either, use a tach and pull plug wires one at a time while the engine runs at about 2000 rpm and watch the rpm drop for each cylinder. Could be a bit of a electrifying experience but it gives you a pretty good idea of what is going on. If the cyl contribution and the idle vacuum is 19" or better with no needle fluctuation, then there is no need for doing a compression test.

[sharpxmen]

those are stupid short, no wonder you can't get it squared on the plug threads, you need an extender about as long as the plug so you have some control, the hose will never be straight as much as you are trying, it can be done but def harder than with a longer one.

[jfrabat]

Well, i got me an extension for the compression tester; I'll see if I can hook it up tonight and report back.  I will also test vacuum (got me a new gauge today) and see how that's doing...  Also got the new TPS and IAC sensors today, so those are also going in tonight...  And the Performance Distributor ignition system should be here before the end of the week, so that's going in soon as well!  Anyway, I'll report back tomorrow with some results (hopefully!).

[jfrabat]

OK, finally did the compression test.  It seems cyl #1 is a bit on the low side, but nothing to worry about (17% from the lowest reading to the highest)...  Could even be that I did not catch the thread properly (AC compressor is in the way).  Here are the readings:

Cyl #1 (119 PSI):



Cyl #2 (136 PSI):



Cyl #3 (140 PSI):



Cyl #4 (135 PSI):



Also took a vacuum reading; seems I may still have some issues in this department, as the idle vacuum is a bit on the low side.  Here's what the gauge read at idle (15 in Hg):



Here's how it read at 1,500 RPM's (18/5 in Hg):



Also rechecked the Fuel Pressure with the new PSI gauge; Sharp, it seems we were both right.  Pressure is closer to what you reported, and it seems the old gauge was just off...  Here's the reading with the vacuum connected (37 PSI):



And without vacuum (44 PSI):

[sharpxmen]

fuel pressure is good, leave it as it is.

was the compression done warm engine or cold?

vacuum is low (as in higher than it should be, 18 or 19 is normal like Art said) given that the engine was warm - are you doing it at sea level or is it higher altitude - that also matters, the higher you are less vacuum you get.

EDIT: this is what i got on mine with the engine cold (but it was hot outside - not extremely, something like 30C), this was a retest, the first time around they were lower but not by much (10 psi), could have been that it was cooler outside.

1 - 155psi
2 - 155psi
3 - 140psi
4 - 160psi

i remember doing it after running the engine until it got to the temperature, can't remember exactly the results but it think it was somewhere in the 180s or so but can't tell for sure, i do remember that the difference with cyl 3 was not as much, it was still lower but closer to the other ones.

[aw12345]

You would prefer no more than a 10% spread between lowest and highest.
Would not hurt to do a leak down test between the lowest and highest cylinders to see what the difference between those 2 is. Again you would should for 10% or less difference.
Vacuum is kinda low could be due to the non stock cam. What running problem does the engine have? Lack of power but runs smooth, misfire or?
Sometimes comparing compression while idling and reving it up to say 2000 rpm and doing this to each cylinder gives you a good idea about valve opening / camshaft condition/ lifters collapsing

[sharpxmen]

Vacuum is kinda low could be due to the non stock cam.

yeah that could be one reason, good catch.

[jfrabat]

I guess I forgot to mention some background info...  Compression test was done dry only, and since I had taken engine apart 2 days prior (but could not run the test due to tje tester issues), the engine was cold (as in there was no oil to help in the compression).  I did not have time to put the TB back together in time to start the engine prior to running the test, so I just went for it as it was.  Its a good point you make abput the vacuum being low due to the cam...  Just in case, though, I am thinking of plugging all the vacuum outlets.except the MAP and retesting to be sure.  Regarding the compression of cyl 1, it could also be that the seal of the tester was not up to par; I feel I could not tighten the tester as well as I did on the other 3 cylinders because of how difficult it was to get the tester in there.  IIRC, I did not even get a full turn in...  so I am not too worried about it.  Oh, and there were no misfires or anything; I just felt it lacked power.  In fact, going up a hill near my house, I normally cam accelarate in third, but now I could not even maintain speed.  But then on Saturday when I took a ride with the top off with the family, it felt fine again.  I am thinking it could have been the broken TPS, to be honest...

[jfrabat]

Received the PD Ignition today, so new coil, Live Wires, rotor and cap are going in today.  Looks like I'll be wheeling on Saturday!

[jfrabat]

Well, it took a while (too much work, thankfully), but I finally got the PD ignition system in place.  When I took out the old distributor cap, I think I may have stumbled into my power loss issue; you see, the old cap had corrossion on 3 of the 4 post, and 2 of them had grooves in them as well.  Here are some pics:









Now, when I put the new system on, I had a bit of a hard time starting the Jeep the first time, so I took off a boot and checked the spark.  Well, not only was there spark, but the jeep started on 3 cylinders, so I put it back on and it fired right off...  Idled better also!

[jfrabat]

I am DEFENETLY doing something wrong...  During my lunch break, I picked up the Jeep in my house to take it to a brake shop to have the rear brakes fixed (I am having issues with the eBrake), and, not even a mile away from home, the Jeep starts acting up.  So, AGAIN, it seems my PD Screaming Demon is dying on me...  WHAT THE HELL!?  It's EXACTLY the same symptoms as it has done in the past.  It starts up fine, then when it warms up, it starts to sputter until it eventually dies.  I drive it back to the house and switched cars again.  I still have the previous coil (plus 2 more as spares), so I'll just put a cheapo coil back on and see how it drives, but this is REALLy starting to get on my nerves. 

Anyway, do you guys have ANY ideas as to what could be going on with my Jeep and the PD Coils?

Felipe

[sharpxmen]

I am DEFENETLY doing something wrong...  During my lunch break, I picked up the Jeep in my house to take it to a brake shop to have the rear brakes fixed (I am having issues with the eBrake), and, not even a mile away from home, the Jeep starts acting up.  So, AGAIN, it seems my PD Screaming Demon is dying on me...  WHAT THE HELL!?  It's EXACTLY the same symptoms as it has done in the past.  It starts up fine, then when it warms up, it starts to sputter until it eventually dies.  I drive it back to the house and switched cars again.  I still have the previous coil (plus 2 more as spares), so I'll just put a cheapo coil back on and see how it drives, but this is REALLy starting to get on my nerves. 

Anyway, do you guys have ANY ideas as to what could be going on with my Jeep and the PD Coils?

Felipe

are you sure it's the coil and not the signal from the PCM, and if the latter could be the issue then i would think maybe the crank sensor could be the problem (acting up once it's warming up). If that's not it and it runs fine with a stock coil then i have no idea other than you got bad luck with the PD stuff but it's very unlikely that 3 of them to do the same thing though.

[jfrabat]

are you sure it's the coil and not the signal from the PCM, and if the latter could be the issue then i would think maybe the crank sensor could be the problem (acting up once it's warming up). If that's not it and it runs fine with a stock coil then i have no idea other than you got bad luck with the PD stuff but it's very unlikely that 3 of them to do the same thing though.

But how come it only happens with the PD coil?  I did notice that there is something loose (well, not loose, but it not solid) in the connector from the ECU to the coil...  Not sure that is the cause, but again, why only with the PD coil?  I could swap the PCM out (I have a spare one) and see what happens... 

I have an old crank position sensor that I could swap out and test, but again, why does it act up only with the PD coil?