Author Topic: Help. Car wont start after head job (Read 3842 times)

bbarnumboy · « **on:** May 28, 2009, 07:31:45 AM »

i just finished completeing my new head job on the m42. everything is back together and the timing is perfect.

only it wont start......it kinda makes a poping every once in a while like it is trying to start. i think i may have the plug wires in the wrong coils...what is the correct coil for each plug can anyone help me out here.

wodcutr · « **Reply #1 on:** May 28, 2009, 10:11:43 AM »

The firing order is 1 3 4 2 with the #1 cylinder at the front of the motor. The coils should be labeled on the cover housing as to which wire goes to which cylinder. If you are standing on the PS of the engine bay the cylinders would be 4 3 2 1 from left to right.

bbarnumboy · « **Reply #2 on:** May 28, 2009, 02:07:56 PM »

hmm ok thanks i think thats how i had it...something else must be wrong.

bbarnumboy · « **Reply #3 on:** May 28, 2009, 06:18:28 PM »

i'm about to roll the car down a hill into a tree. it won't start and the wires are fine. something electrical is not right. i hate diagnosing electrical.

beemer1 · « **Reply #4 on:** May 29, 2009, 06:59:35 PM »

What about the 2 sensor connectors located under the intake? I think one was a crank position sensor? The connectors look identical maybe you reversed them :confused:

Steve

twright · « **Reply #5 on:** May 29, 2009, 09:01:22 PM »

Fuel lines under the intake reversed?

DesktopDave · « **Reply #6 on:** May 29, 2009, 09:13:28 PM »

Did you do the stomp test? I know it sounds stupid, but it's a start. Test resistance on the cam & crank sensors. You're getting spark & fuel, get a timing light on it and see where #1 is firing.

Go get that electrical troubleshooting manual too. Worth it's weight in copper.

Jimmy Lewis · « **Reply #7 on:** May 29, 2009, 10:02:53 PM »

What all did you disconnect when you pulled the head? Just check for fuel and spark, and go from there. You can eliminate a lot of things just by knowing which one you aren't getting.

Electrical troubleshooting is really easy, you just have to know what you are looking at and what the numbers should read. Search for the pdf of the electrical troubleshooting guide and get to work.

bbarnumboy · « **Reply #8 on:** May 30, 2009, 02:27:15 PM »

i have fuel and spark is on with the timing light and i checked the resistance of the afm coil packs crank sensor and cam sensor, and all are in good working order.

do you guys think that if i have the 2 coolant temp wires switched around that it would cause a problem?

and as for the fuel lines i am pretty sure there was only one logical way for them to hook up so they should be in correctly.

i did a stomp test and no codes just the default 1444 meaning there is no problems.

what do you guys think about the coolant temp wire question?

and if i got the knock sensors mixed up to would that do this problem. i dont know why the two coolant sensors wires fit in each other. how dumb.

and when i did the head the whole timing covers and compontnets were replaced and the whole lower and upper manifolds came off because i cleaned everything up. so everything got disconnected.

bbarnumboy · « **Reply #9 on:** June 02, 2009, 02:11:13 AM »

thanks for the input guys. it turned out to be that the coil pack wires were not connected to the coil packs in the correct order from the previous owner. so i assumed they were when hooking the plug wires back up. but it has now been fixed and the car runs amazing, and very very smooth. thanks guys

DesktopDave · « **Reply #10 on:** June 02, 2009, 07:41:54 AM »

That's good to hear...aren't they great cars? Good work on locating the problem too...I don't think that the coolant sensors make much difference one way or another. Same for the knock sensors.

bbarnumboy · « **Reply #11 on:** June 02, 2009, 06:18:42 PM »

cool that is good to know. it had a intake leak and i am fixing that tonight and the cracked thermostat housing but it looks amazing now with all the new parts and powder coating. here is a pic for ya guys

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