[blackstangt]

I have changed my:
air filter
distributor
fuel filter

Checked my:
timing
fuel pressure

The car is popping, which causes a loss of power. It sounds like it may be coming from the intake or exaust, possibly both. Throttle response is gone. It is an intermittent problem, but the car is certainly not running as it was a few days ago. Until that time, the car ran fine, making a cross country trip a couple months ago.

I ran the fuel down pretty low coming home from work, which was when I noticed the first pop.

The idle seems to have decreased to about 650 RPM which is only an issue because it wouldn't get that low even when warm prior to the last few days.

I am going to go check the plugs for fouling or lean mixture, hopefully some ideas when I return. The only thing I can think of is an intake gasket leak (vacuum), and that takes ordering parts to fix.

Please help if you have had similar problems, and thanks for at least looking at the post.

[HISSIN50]

Have you checked codes?
How is Fuel pressure while it acts up?

[DROPTOPFIVEOH]

the car i just puchased was doing that same thing ruff erratic idle popping back and ended up being the timing was off and the mass air meter plug was making a bad connection causing the computer to lean the engine up and began to detinate. maybe this will help....

adam

[blackstangt]

Originally Posted by HISSIN50

Have you checked codes?
How is Fuel pressure while it acts up?

I probably should mention that the popping is only while I am driving it, the fuel pressure is normal (38-40 lb) when there is hesitation and everything else though with the car still.

I haven't checked for codes yet. I am not getting a check engine indication, but with the mods I wouldn't know what codes would show up normally...

Using the guage in the dashboard, the oil pressure seems lower than usual, possibly indicating a vacuum leak?

The spark plugs were a little white, but I remember them being a little white before. At least I am sure it's not running rich though.

I can't be running it and making noise anymore tonight, but I will be looking for vacuum leaks and cleaning the MAF tomorrow. I have a few coils laying around, will probably try them too.

This seems to be a progressive problem, starting as a pop every once in a while, and now the car is barely driveable.

[HISSIN50]

The CEL need not be on (or ever have illuminated) to store codes. That is the place to start.

The Stock OP gauge cannot be used for any determination of anything (it's an on/off switch).

[blackstangt]

Originally Posted by HISSIN50

The CEL need not be on (or ever have illuminated) to store codes. That is the place to start.

The Stock OP gauge cannot be used for any determination of anything (it's an on/off switch).

I got codes 81, 84, and 85.

What would you think, based on the symptoms and codes?

I just checked vacuum lines and sprayed carb cleaner around to check for leaks, with no noticable change in performance.

I'll be able to get a ride to a parts store, any recommendations? I was planning on getting dielectric grease and hitting the mass air, distributor and any other electrical connections I can think of.

It seems that there is something prohibiting it from running the correct mixture, running lean...

[liljoe07]

Do you have smog on the car, or a functioning EGR system? If not then......

Run the codes while the engine is running. There may be more. The ones you listed are KOEO codes.

[blackstangt]

No smog pump, I'm going to check those codes, never done it before...

[blackstangt]

Based on the codes, the EGR seems to be bad, I disconnected it, giving me a 'check engine' light for now, but I will replace it with a new one or the delete plug.

As long as the check engine light is on, it seems to run fine, but I will be continuing to work on it tomorrow.

[blackstangt]

Disconnecting the EGR didn't really help, I think it is only running well when it's warmed up, I'm going to reconnect it.

What would cause the car to backfire out the intake on city streets and run seemingly fine on the highway?

I changed the cap and rotor the day before this all started, going to change back to the old one right now.

[blackstangt]

After changing back to the old cap and rotor, everything seemed to go back to normal. The car ran great all the way to work.

On the way home however, I got a single pop out of the intake, and the idle rose up to 2000 RPM. Later, the car was putting out inconsistent power while driving and the check engine light came back on.

I have essentially put the car the way it was when it ran well.

New codes after the drive home: 26, 32, and 67

67 is nothing, 32 is EGR again, 26 is MAF... I should probably try switching the MAF sensor from another mustang into mine, just to see if it works, I'm tired of buying parts I don't need.

[Brandon11010]

Well i know a stuck open egr will cause drivability issues, and egr only opperates at cruise, so if you have a stuck open egr it would run fine at highway speeds and terrible at idle and off idle opperation..There is a egr vacuum solenoid on your right fender tword the back, has a little cap on it, if you remove the cap there is a little foam filter inside, if the filter or the vacuum hole is plugged the egr will open, or any vacuum loss to that solenoid will open the egr. Might be somethin ya wanna glance over. If your car is running and you put your finger over that vacuum hole and your idle drops and runs rough you know that soloenoid is working. Hope that helps

[blackstangt]

Originally Posted by Brandon11010

Well i know a stuck open egr will cause drivability issues, and egr only opperates at cruise, so if you have a stuck open egr it would run fine at highway speeds and terrible at idle and off idle opperation..There is a egr vacuum solenoid on your right fender tword the back, has a little cap on it, if you remove the cap there is a little foam filter inside, if the filter or the vacuum hole is plugged the egr will open, or any vacuum loss to that solenoid will open the egr. Might be somethin ya wanna glance over. If your car is running and you put your finger over that vacuum hole and your idle drops and runs rough you know that soloenoid is working. Hope that helps

Unfortunately, that has never worked, I know the trick where you put your finger over it and seen it work on other cars. Mine never did anything though, still doesn't. I have the vacuum line that goes to the EGR blocked off right now, so it shouldn't be able to open, right?

[HISSIN50]

Originally Posted by blackstangt

Unfortunately, that has never worked, I know the trick where you put your finger over it and seen it work on other cars. Mine never did anything though, still doesn't. I have the vacuum line that goes to the EGR blocked off right now, so it shouldn't be able to open, right?

Unless the valve itself is being held open by a piece of carbon, otherwise leaking, etc.

[blackstangt]

I think I fixed the problem, I was using parts cleaner on all of my connections and on the mass air and I noticed that the EGR electrical plug had come loose. The clip holing it on was broken on one side, so I put a zip-tie on it the other day, but it seems like the zip tie was loose (probably caught on something when I tightened it).

I tightened the zip-tie up (in daylight this time) after putting dielectric grease on the connectors, check engine is gone.

So basically the only difference between now and when I started is some parts cleaner and dielectric grease. I guess that's what happens with a 20 yr old wiring harness.

In a couple days, I will put some of the things I changed back on, one by one, so I can see if they're good. Those are a cold air intake, cap and rotor, and new distributor.

Thanks for all of your help though, if I hadn't run the codes, I wouldn't have thought of the EGR.

[the pony boy]

dont ya love it when its something so small!