Jump to content

Rough Idle on occasional longer start


Recommended Posts

So I have a small problem. On occasion ill start up my pathy and itll take maybe an extra couple seconds of crank time. Battery and Alternator are new. And on other times, she will start up and have a rough idle, then set off the MIL. If i rev it up a little bit the idle will smooth out and turn of the MIL. Any thoughts?

Link to comment
Share on other sites

I would think that a cracked exhaust stud or a clogged MAF sensor might do that but thinking about it while I write this another thought occurred to me: does the MAF itself have a good ground, i.e.: a new ground wire to bare metal? If not there is a new part that (used to be available) is supposed to add a wire to that connector. There are a few threads in here that speak to that subject including part numbers and how-tos.

Link to comment
Share on other sites

I would think that a cracked exhaust stud or a clogged MAF sensor might do that but thinking about it while I write this another thought occurred to me: does the MAF itself have a good ground, i.e.: a new ground wire to bare metal? If not there is a new part that (used to be available) is supposed to add a wire to that connector. There are a few threads in here that speak to that subject including part numbers and how-tos.

I think it might be the cracked exhaust stud as sometimes when I start it up I get a ticking noise from the driver side. But how would that cause a rough idle?

Link to comment
Share on other sites

I would start with checking the fuel pressure, and then the impedance (ohms) of the injectors. As well as the codes. There is a how to here for the codes. That will likely lead you on the right track. Recent tune up?

Link to comment
Share on other sites

I would start with checking the fuel pressure, and then the impedance (ohms) of the injectors. As well as the codes. There is a how to here for the codes. That will likely lead you on the right track. Recent tune up?

Yeah it had a recent tuneup, (as well as intake gaskets replaced, all fuel injectors replaced). Would a missing knock sensor cause something else with things like this? I found a cable behind the intake and it looks like it could have gone to a knock sensor. I am not sure if was missing from factory because i didnt put the intake manifold back my father did.

Link to comment
Share on other sites

I can see how a missing knock sensor could cause a rough idle and throw the money light on.... it just plugs in behind the intake but if you have large hands and little dexterity it's going to be a struggle. You have to remove the upper intake plenum to even get to the knock sensor.

Link to comment
Share on other sites

I am actually have nearly the same problem with my 92. It starts great the majority of the time but on occasion it will crank over maybe twice as long and then start. The check engine light is almost always on and when i read my codes it says "code 51." It also has a rough idle but as soon as i give it gas it clears right up, but the check engine light stays on. I still need to check my fuel pressure to see if i have a leak. Any other thoughts?

Link to comment
Share on other sites

  • 2 weeks later...

So I was in class the other day conducting a manual load test on our battery, and when It came time for my turn, my starting sounded like it wanted to start as if fuel was in the system. In short it sounded very erratic and didnt crank as the other cars did. Could the starter be weak or be causing the problem stated above?

Link to comment
Share on other sites

  • 2 weeks later...

I think i found the problem, during class i disconnected the ignition coil before conducting a test. Found that it was very chalky, white, and the connector was broken and corroded. I am gonna be replacing the ignition coil and coil plug wire.

  • Like 2
Link to comment
Share on other sites

  • 4 weeks later...

A little wipe of dielectric (it's actually an insulator, but it squeezes out of the way as you bring the contacts together) might prevent it from corroding again, so it's not a bad idea. I wouldn't call it required, though.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...