dead cylinder

fifty$240 · Mar 18th, 2006, 09:35 PM

Hi all:

In my 91' 300TT, i have a hesitation problem. i changed the fuel filter and all of the plugs with platinum ones. but i still have the same problem. it feels as if i have a dead cylinder. I started to pull off the connectors to the coil packs and found that #1 cylinder has no drop in RPM. I swapped the coil with another cylinder and still the same problem. i pulled the plug and it was wet, i did a compression test and it was at 110PSI. and i used a spark tester to see if there was energy getting to the plug and it was lighting up. I am out of ideas. please help

v/r
Luis

fifty$240 · Mar 21st, 2006, 09:54 PM

<<bump>>

Please, does anyone have any ideas?

**Spongerider** · Mar 22nd, 2006, 10:14 AM

Quote:

Originally Posted by fifty$240

Hi all:

In my 91' 300TT, i have a hesitation problem. i changed the fuel filter and all of the plugs with platinum ones. but i still have the same problem. it feels as if i have a dead cylinder. I started to pull off the connectors to the coil packs and found that #1 cylinder has no drop in RPM. I swapped the coil with another cylinder and still the same problem. i pulled the plug and it was wet, i did a compression test and it was at 110PSI. and i used a spark tester to see if there was energy getting to the plug and it was lighting up. I am out of ideas. please help

v/r
Luis

Did you check your injector on #1 cylinder?

fifty$240 · Mar 22nd, 2006, 09:22 PM

short of taking the top half of the engine apart, is there any way to check the injector? Do i need a consult unit to do this? Or can a dealer check it for me? anyidea of the dealer cost? Sorry for all the questions, its just real frustrating for me. Thanks for the reply!!

Luis

Marc Z31 · Mar 23rd, 2006, 02:06 AM

Sounds like you have a bad connecter at the coil. It is a very common problem with the Z32 cars, it happened to my friend's car on saturday. Make sure the little rubber seal in the electrical connection on the top part of the coil is not twisted up, and you're a getting a good connection. If the plug was wet, then it's a spark issue. Even if the injector was bad, and dumped fuel all the time, the spark plug would be very sooty and possibly wet.

99% sure it's the coil's electrical connector.

fifty$240 · Mar 25th, 2006, 03:11 PM

ok.

I tested the continuity between each cable and it's female connector in the coil plug. I get continuity between each of the three cables. I don't know where to go now. Any other ideas out there???

v/r
Luis

apudapus · Mar 26th, 2006, 11:45 AM

110psi in the cylinder is way below what it should be. you should do pour oil some oil in the cylinder then re-do the compression test. if the compression increases, it's your piston rings (which i doubt).

if the compression doesn't go up, it's the head gasket (i doubt) or the valves.

you can do a leak-down test to confirm.

a wet spark plug: wet with oil or wet with gas?
a leaky injector is something you can look into, too.

fifty$240 · Mar 26th, 2006, 10:45 PM

Last night I was reading the manual and realized i did the Comp Test wrong. I didn't hold the throttle open. Thats why it was so low. Not enough air was getting in the cylinder to increase the ratio.

I am going to try some of the diagnostic that i read in the manual. I am going to pinch the hoses to the pcv valves and see if the revs pick up.

I'll redo the compresion test anyway to be sure.

js9krcr01040 · Mar 27th, 2006, 12:50 AM

Quick way to test the injector is with a long skinny screwdriver, jut plant it on the top of the injector and listen into the handle for the pulse...

apudapus · Mar 27th, 2006, 12:57 AM

be sure to do the compression test across all 6 cylinders so you have a comparison. there shouldn't be more than a 15 psi variation.

fifty$240 · Apr 20th, 2006, 06:04 PM

OK all. Thanks for the info. I have come to the conclusion that my number 1 cylinder is no firing due to the fuel injector stuck on open. hence dumping too much fuel in the cylinder and making the mixture too rich to burn (therefore, no combustion) which is why when i disconnect the coil pack there is no change in RPM, but when testing with a plug, there is a spark. SO, the question is: is there a way to un-stick a stuck fuel injector without having to replace it, or should i replace it. and if so, should i replace all six (which is over $1000) or just the one bad one. All ideas are welcomed.

V/R

Luis

BlackZhawk · Apr 25th, 2006, 08:30 AM

I know it is pricey but your best bet is to replace all six injectiors. Being that the ones installed right now are prob the ones that the engine was built with they might be ready to go soon too. So to cut the cost of having the work done multiple times or if your going to do it yourself keep the headache to only one, replace all six.