ajricker

I've been trying to sort out a cold start rough issue. I read as many posts on this as I could. This is what I've done so far. When I had the engine out I replaced all the sensors so I didn't think it was the temp-II sensor but I replaced the connector for it and did check the resistance on it cold and it measured 3,000 ohms on both pins. I read some more and decided to check the MAF so I pulled the air filter box and unplugged the MAF and the car fired right up, didn't die and seemed to idle fine. Does this mean that the MAF needs a rebuild?
Once the car reaches operating temp it with the MAF plugged in it seems to run fine. But smells a little rich.

GlenL

That car has a "MAF?" What's the year and model?

ajricker

86.5, info in my sig

Mrmerlin

yes you need to get a good MAF or a fresh rebuilt MAF.

also consider swapping in a new O2 sensor use a factory part,

then you should also have a fresh IAC valve installed if not replace it , it wears out and will stick due to the brushes wearing holes into the armature its a wear item.

and make sure you have a good TPS short wire, the male connector portion breaks at the connection point above the watert bridge, Roger sells them.


Also remove the vacuum lines for the dampers and the FPR as a leak in one of these parts would not be unusual and could also casue part of the running issues,
if any one is leaking then replace all 3 of these parts.

NOTE also consider swapping in a set of Porken chips,
in that case you would replace the FPR with an 87 S4 FPR.

Once all of these parts are fresh and the ignition wires and coil wires are good then your car can be tuned and it should run properly.

It sounds like a lot of stuff to replace,
but once all of it is fresh then your car will run perfectly for a very long time.

NOTE is is very common for all of the parts i have listed to be in need of replacement,
only doing one or two of these parts will almost guarantee you will have further issues down the line

ajricker

New IAC valve on order. Everything else has been replaced when the engine was out. All new vac lines. Porken chips, new FPR, new Greg Brown fuel lines, headers, airpump delete, cat delete,x-pipe, new O2 sensor. I should have done the IAC valve when I did the intake refresh. But I was trying too slow the bleeding. I noticed I didn't line one of the clamps up well when putting the old one back on and now it's going to be a pain in the a** getting it off.

John Speake

You need to follow the WSM routine for setting the MAF and idle speed..... when cold the LH runs open loop, so running is critically dependant on MAF setup and calbration.

You'll soon know if your MAF needs replacing if you can't setup the specified idle CO (i.e. idle pot goes to max)

ajricker

Thanks John. I'll have to see if I can figure that out. I think I saw that in the WSM somewhere. It wasn't real clear to me at the time. I'll have to see if I can find it again.

ajricker

I don't have the tools to run the routine for MAF and idle speed but I did pull the MAF and check resistance on pin 3 to 6 and pin 4 to 6 and came up with 133 ohms om both pins. I don't know how much adjustment is left on the screw. The cap is off. So it has been adjusted at some time. Is there a rough setting that it should be at to start?

Mrmerlin

380 ohms is nominal if your MAF is old then it needs to be rebuilt to assure the injection system will get the proper fueling and thus restore original performance,
this is also critical when fitting Porken chips

ajricker

Would it be worth trying to adjust it to 380 ohms first before I order up a rebuilt? If it runs better after the adjustment I cuold try to find someone with a Porken blinker setup.

ajricker

OK, I adjusted the MAf to a 380 Ohms and it starts right up. No instant die or rough idle. New idle control valve should be here tomorrow. I'll install that and then see if I can hook up with someone with a blinker setup. I don't want to buy a new MAF yet if I don't have to, As I think I need a new fuel pump. It was making noise after a 2 hour drive last Sunday. I also need to do the drive axles yet too.

ajricker

Just took it for a short drive. Seat of the pants, it definitely felt better. More responsive.

Mrmerlin

the fuel pump will make more noise when the car has been driven for a long time
IE over an hour steady and the fuel tank is low, this because the fuel in the tank is being heated as its run trough the injection system.

adding fresh fuel will cool the pump and it will run quieter.

Also you can add about 6 oz of MMO to the gas this will assist it in staying lubricated

ajricker

Thanks Stan. The tank was approximately half full at the time. I fueled up before I left for the day. When I fueled up the next day it only took 11 gallons. Should it still have been making noise. It was audible in the car. At first I thought it was the rear A/C.

Mrmerlin

have you tried adding the MMO?
my pump in my 88 runs louder sometimes usually after a long drive and the fuel is low
yes the pump can be heard inside the car. and its a bit louder,
I replaced the pump when I rebuilt the car, it has about 10K miles since this was done