Misfire after fans come on.

[SolidState]

I am really chasing my tail on this one.

The car ran well when I got it, but I discovered oil in the plug wells and decided it was time for a 60k. I replaced everything except the plug wires, as they were really nice Magnacore wires. More on that later.

Once I was finished buttoning it up, it ran well. Until the fans kicked on. The idle raised, it ran fine. The rans kick off, and then the car seems to sputter, and the idle a little loopy. Although the tack doesn't really move.

Fast forward to about a month ago. I replaced the magnacore wires with some brand new Accel wires from SHOnut. The car ran well, idled better, was smoother, until the fans came on.

Last weekend, I tried to replace the CAM seals, but ran into a major issue with the crank bolt (another thread). I was unable to remove the harmonic balancer, but was successful in replacing the CAM seals.

This morning, the car seemed to start rough and run rough. So far, I've checked:

- the plugs, and they are white and properly gapped. Plug wells are dry.
- unplugged the MAF. The car nearly died, but recovered. Clean the MAF for good measure.
- replaced the air filter. Mostly for good measure.

Other notables:
- Restarts when warm are rough. Could be a weakening pump, but the car runs fine otherwise.
- Vacuum hoses are looking old. But none appear to leak. I pulled a couple, and the idle would rise, smooth out, then drop and stutter.

What puzzles me is that it runs okay, until the fans come on.

any ideas?

 

[SHO#7]

How about an idle relearn. That is a very easy and basic place to start, or have you been there already?

Mike

 

[SolidState]

Did that. Good idea though, thanks.

I am wondering if a cam being off my one tooth, vaccum leak or bad grounds is my problem.

 

[SHO#7]

If you turn the AC on does it get bad too, or just when the fans come on due to engine temp?

I do not think you have the timing off a tooth. The temp would not make any difference IMHO. If the timing is off, it is off.

Hmmmm.... Think think think.

Mike

 

[SolidState]

The AC isn't currently functional, but when it did, the results were the same.

 

[Storm-Chaser]

What do you mean, when you say, " .... AC isn't currently functional, but when it did, the results were the same.... "


What about the IAB? Most vehicles elevate the idle rpm when the A/C is on, to compensate for the increased engine load. Many vehicles engage the compressor clutch whenever the internal blower fan is engaged. You might try to see if turning on/off the blower motor (or even the A/C even though it isn't functional) to see if you get this change in rpm. I'm not sure which relay controls this, but a lack of change in rpm may indicate the relay that adjusts/controls/signals the idle speed is not functioning.

You could also try a CCRM swap to see if the problem replicates, if you have a spare CCRM module.

 

[SHObill]

Keith got em both! Clean the IAB & give the CCRM a sharp smack to fix any attitude she may have. I have found a sharp smack to the CCRM resets all the relays, the contacts do get high spots from arcing & that shakes em up. Also clean & add grounds as this improves driveability & IMO this motor is not well grounded as it relies on a bunch of small wires that just screw into the uinbody & there is no Alt housing to frame ground! Many of the small wire grounds I have found on many cars have been loose/coroded!

 

[SolidState]

I hear a popping/gurgling from the fuel tank. I guess I'll throw that 155lph Walbro in it this weekend.