engine stuttering

[Money pit Beretta]

Ok so
1. 116.030psi
2. 130.533psi
3. 101.526psi
4. 123.282psi
5. 116.030psi
6. 130.533psi
Boy number 3 is low!

[Berry]

the mechanic said the compresison isnt that bad. but maybe it IS bad
could a burned or bent valve be the reason?
the peak of stuttering repeats every 3-5 seconds. what could that be?

[Money pit Beretta]

Could be a bad injector or two. The only way to test is a bit of a pain. You would have to pull the upper and have them tested. Or pull the upper, take out the rails(with injectors) and put cups under each injector.
This is what I did on another car. Pulled the rail, put the cups under the injectors and then unpluged the ICM. I had to hold the throttle open at WOT to get enough fuel out when someone else was cranking the engine.
I just had a guy try that on a 95 Z24 and with the throttle at 100% nothing came out. Two guys jumped in and said that unpluging the ICM killed the injector signal. Also that WOT when cranking cuts the fuel(to clear a flooded engine).
I'm not sure why it worked for me, but I was holding the rail and the throttle at the sametime. That could mean that it was not at WOT all the time and could have been 75% sometimes. Well I'm still having trouble with that car and could have changed things(I don't know).
What brand of O2 are you running? I have heard that a Bosch can make misfires and running problems. Run an AC(if you can still get it, Rock Auto will send you a Bosch) or a Denso.

[Berry]

thanks money pit!!
you mean with "upper" the upper intake?
I dont know which O2-Sensors I have, where are they located?

+++EDIT+++ Alright they are located on the exhaust manifold and/or exhaust pipe

[Money pit Beretta]

Yes the "upper" is the upper intake.
I think you may be able to unplug the O2 for testing, but I wouldn't let it run long. The default for the O2 is very rich. If you have the money then I'd just get another one and not take any chances. You don't want to kill the catalytic converter. That is if it's not dead and or clogged anyway, which would also give you problems.

I don't know of any way to check the catalytic converter other than banging on the bottom to see if anything is loose.

[Berry]

hey I got news!!
I did today an emission test. the mechanic said
the engine runs lean. that means that the fuel filter could be
clogged!
the emission documents show
that the hydrocarbon diminished the
last 20 years from 56 ppm to 4 ppm.
so changing the fuel filter could stop
the stuttering of the engine.

anyway, its time to change the fuel filter.
I will buy it on rockauto. and because I have to pay
a shitlot for shipping I will take a PCV too - just in case.
do you have any recommendations which
brand I should take? acdelco? pentius?

[Money pit Beretta]

Delco is fine or Wix if you can get one.

[Berry]

Thanks for your recommendation. You re one of the guys who most frequently answer my questions
I ordered a Wix.

[Money pit Beretta]

Your welcome. Wix also makes one of the best oil filters by the way.

[Berry]

I ve changed the fuel filter and the pcv. still the same issues.
I try the ignition cable. it looks fuckedup

[Money pit Beretta]

Berry I have a cool little spark checker that you just set on top of the wire and it lights up. It's a Lisle #19380. See if you can find one or one like it in your area.

[Berry]

thanks pit! I'll check that up with a spark checker
the next step would be to open the upper intake. to have a look to the valves of cylinder no.5 and to the injectors.
first I should order some intake- and valve cover gaskets

[Money pit Beretta]

The intake is set up like a cross ram. What is on the right ends at the left and so on. There will be no way to see the valves without taking the lower off.

[Rettax3]

I wouldn't worry about the valves. 101 PSI is pretty low, and the range for compression between cylinders is too wide so that could be your problem, but a valve bent so badly that you could tell from the stem by looking through the intake... No.

To check for codes on your OBD1, look under the dash for the diagnostic plug. Look at the connection ports, notice only a few ports have metal connectors in them. Put a piece of wire in to connect the two ports that have metal tangs in them that are next to each other, "A" and "B", upper right two, I think. Turn the ignition key on, but do not start the engine. Look at your "check Engine" light, it should be flashing. It will blink once, then twice. This means 12. It will repeat each code three times. 12 just means that it is in diagnostic mode from the jumper wire you put in. If it flashes 3 times, then three times again, and repeats that three times, it is telling you that you have a code 33, for example. OBD1 does not require any special tools, which is really nice.

I also wouldn't worry about the catalytic converter being plugged -if it is plugged so badly that you are having idle problems, the engine won't run right at higher RPMs, and would be even worse.

Best guess is a bad spark-plug wire, or a bad coil, maybe even the ICM. An in-line spark tester is a little harder to use (but still very easy), and would give you better information than a tester like Money Pit mentioned. Although the tester he mentioned is the easiest, it may not tell you if you are losing spark to ground.

Also make sure your fuel pressure regulator isn't leaking internally be removing the vacuum-line to it while the engine is running, look for gasoline coming out of it at the port. A bad MAP sensor or (as [Money Pit already mentioned) a bad O2 sensor could cause this, but you should get trouble-codes for either of those. A leaking injector could also be responsible -do a fuel-system leak-down test with a fuel-pressure gauge to see if one may be stuck partly open.

Good luck! Let us know what you find.

[Berry]

it's great to get so much help from you guys. this makes me feel not alone with my engine probs

I haven't got any errorcodes. only the handshake code no12 repeating more than 3 times.
I 'll check the spark plug wires.
But the only thing is, I don't understand why the engine only stutters in idle but not with high RPM?
If the spark plug wires or the injectors are bad, then the engine should always stutter, isn't it?

how should I do a fuel system leak down test?