carkrazy1987

I bought a 94z m6 about a month ago with a blown head and head gaskets. i have rebuild then engine since then and have been driving the car alil here and there. car runs fine once started, no over heating or abnormal noise or anything. my problem is as listed...

-Hard Start, Takes 2-3 tries before it starts.
-Have tried letting the pump prime, then starting, no change.
-Have tried to prime turn key off and reprime again no diff.
-Have put a fuel pressure gauge on, no fuel pressure loss.
-42psi after prime and holds for about an hour at 40-42psi.
-Checked with Tech-1 and temp sensor reading correctly.
-Ohmed out all injectors all check out fine.
-I Have DTC 18, but intermittent. Will clear and will come back eventually.
-I Have Good Spark During Cranking.
-Does not happen anymore when vehicle is warm or cold, or weather is warm or cold
-Intermittent misfire happens when sitting at idle for extended period of time, and DTC 18 will set

If I can think of anything else i will add to my list.

I am at a loss of what could possibly be causing the problem. any help is greatly appreciated

Charles

Guest47904

It would appear that you have a wiring issue with at least one injector. The majority of the time it's the connector. Even if it checks out with a noid light, it doesn't mean the connector is making good contact with the injector.

You pretty much know the mis and the 18 are the same problem. What you don't know is it responsible for the hard starting issue. You can check that out by squirting fuel in the intake to see if it starts easier.

carkrazy1987

Do you think the hard start could be due to the code 18 and injector curcuit issue?

Guest47904

Think I told you how to figure it out

carkrazy1987

well so far no luck, i have gone threw the wireing from the injectors to the pcm, and found no problem. i have even decided to reterminal the injector connectors cuz a few seemed abit loose. i cleared the code and it came back a lil later. spraying fuel in the intake seemed to help abit. any other thoughts? anything else to look for?

Guest47904

Does that mean you actually ohmed the wires from the injector connectors to PCM connector?????

How about pulling the injector connectors with the engine on one at a time until you find one that doesn't cause the engine to run worse?????? Could this then be the one to focus your attention on?????

carkrazy1987

yes i did ohm out the wiring from the injector connectors to the pcm connector. checked out ok. i pulled the connector from the injectors one at a time while running waiting at least 1 min between each and found injectors for cylinder 2 & 4 changing the vehicle idle the least. so im assuming from this test that i should replace the injectors?

Edit: It also seems during cranking, and also once i get the car running it seems its running rich. strong fuel odor from the rear.

Guest47904

What does the condition of the plugs tell you?

What does the O2's readings indicate? Are the fuel trims inline with the O2 readings?

carkrazy1987

i will check those things when i get a chance today. i dunno if the plugs will show much they are brand new and have maybe 3 hrs of run time on em total. but i will look anyways and see if anything shows up. and what should the o2 reading be?

thank you
Charles

Guest47904

O2's should be switching quickly from .100 to .900

carkrazy1987

so i checked the readings today. i used a gm tech 1 to check all this data here is waht i got...

Right bank ho2s - 300mv - 800mv Closed Loop
Left bank ho2s - 4mv - 750mv closed loop (Bad o2 sensor?)

(edit) also pulled a couple plugs showing rich. probly due to not letting engine run for long while trying to diagnose the hard start issue.

The rest of the data is as follows

engine speed - 800 rpm
desired idle - 800 rpm
engine run time - 27min
knock sensor - ok
fan ctrl pcm a10 - on
fan ctrl pcm a11 - on
injector fault - no
tcs/asr active - no
air control - off
fuel evap purge - 0%
egr duty cycle - 0%
system voltage - 12.9v
idle air control - 29
learned iac - 32
inj p.w. bank 1 - 2.5-2.7msec
inj p.w. bank 2 - 2.6-2.8msec
lo res signal - 18.3-19.1 msec
hi res signal - yes
knock retard - 0*
knock signal - yes
spark advance - 20*-22*
mass air flow - 8.7-9.5g/s
fuel trim cell - 16
fuel trim enable - yes
ST fuel trim bank 2 - 112-118
LT fuel trim bank 2 - 108
ST fuel trim bank 1 - 108-111
LT fuel trim bank 1 - 108
Right bank ho2s - 300mv - 800mv Closed Loop
Left bank ho2s - 4mv - 750mv Closed Loop
T/P - 0.60 volts
Throttle Angle - 0*
MAP - 32-34 kpa 1.14-1.18v
coolant temp - 196*f
air intake temp - 86*f

93transam1234

Try switching those 2 injectors to other Cyl's and see if the problem follws the injectors or stays with the wiring.

I also have hard/long start and rough idle when cold. After checking everything i could i chalked it up to having some condensation inside the Opti.

carkrazy1987

the intermitent miss seams to have gone away the dtc 18 will come back every now and then but i dont see anymore or feel anymore miss fire . so fixin the wireing seamed to fix it. but my hard/long start is my problem. i cant drive the car cuz of how long it takes to start it. i get closed to killing the battery sometimes. and if i keep going the way im going now imma burn the starter in a week.

carkrazy1987

id like to thank those who have helped me try and diagnose my problem. after another day of fooling around with it i figured out i had a faulty ignition switch. the switch would not allow enought amp to get to the power side of the injectors. all wireing checked out and had proper voltages when running, but durring cranking it would draw down and not supply enought power to the injector curcuit. this was not noticable with a test light or meter. i had take a jumper wire and jumped the pink wire coming into the fuse block to power the injector curcuit and gave it 12v from the battery. thus when i turned the key it would have full power and started right up. again thank you for the help guys