Fuel reg question

[ebk06]

A little quick history. I was having idle issues a while back and finally pinned it a bad power boost (car kept dying when i was stopping). Got that replaced and I noticed now the car is blowing black smoke and at a stop light the car will start to idle surge again after a minute or two. I pulled the codes this morning and only got a code 11.

When I picked the car up yesterday we tried setting the TPS (which is brand new) and couldn't get it set below 1.* without the car dying. Now Ive gone through the surge idle check list, again. With the black smoke Im thinking the fuel pressure regualtor is bad. I need to check it but was wondering if a bad FPR would cause the idle to surge when the car is in neutral? Also would this cause me to not be able to set the TPS correctly. I plan on trying to clean the IAC also just to see if that helps. Any input would be appreciated.

 

[RatStang]

Yes... clean the IAC.

If you have a fuel pressure gauge installed, check fuel pressure with the vacuum line on and then again with it off. If you get a variance then your regultor is probably ok.

Setting your TPS to specific X voltage is pretty much a useless task. Your TPS is referenced by the computer during startup and voltage scaling is adjusted by the EEC. Really the only thing you need to be concerned with on the TPS is whether it works or not.

For further troubleshooting tips, see the Technical Thread Index at the top of the 5oh Tech forum. Look for JRichker's Surging Idle Checklist.

GL!

 

[ebk06]

Ive followed the Surge Idle Checklist.

To be more specific about the TPS issue. We tried setting the idle with the IAC disconnected and couldnt get it to idle below 900 rpms without it dying. So from there we set the TPS to to lowest we could get it to which was 1.*.

Now would a bad regulator cause us to not be able to get the idle below 900? The surge checklist says it should get to 500-600 rpms or else it would be a vacuum or mechanical problem. Also the vacuum lines have been changed out recently and quadruple checked to make sure they werent deteriorating already.

The guy that was helping me was suggesting I clean the throttle body too. Would it be best to remove it from the intake or would spraying it while attached be good enough?

 

[RatStang]

I'd try spraying while attached first, although I don't think your issue is TB.

That 600 RPM should be observed (set, whatever) after the engine is warm.

Have you tried disconnecting and reconnecting the mass air sensor with the car running? If there's no change in syptoms then your peoblem lies within the MAF or associated wiring.

 

[ebk06]

No, I guess I should have added its an '87. Speed density.

We tried setting the rpms after we drove it around a bit so it was warm. The black smoke and gas smell really has me thinking its the fuel reg. Its at the point of hoping its getting too much fuel and thats causing the idle surge.....but im not sure.

 

[RatStang]

Have you swapped cam, heads, or TB on this setup?

 

[ebk06]

No the cars completely stock except exhaust, which doesnt effect anything obviously.

 

[RatStang]

Here's what comes to mind:

Idle is actuallyset my the EEC and NOT by the set screw on the throttle body. So what you might try is setting that screw (regardless of RPM) so that you get a smooth idle. Then drive it and get it warm. Allow time for the EEC to compensate if it's going to. Might be a good idea to reset the EEC Prior to doing this.

You may still have a vac leak (though you're not able to find it readily)

The Barometric sensor may be bad (this will cause the EEC to stay in Open Loop even when the motor is warm). Pre-set fuel tables too rich causing the surge.

You could in-fact have a bad fuel regulator but you'll need to rule that out with a fuel pressure gauge.

Your codes... Did you do engine on and off?

 

[ebk06]

I was thinking the same thing about the vacuum lines. I guess I need to just replace them again since its cheap to do.

I checked the codes this last time doing KOEO. I tried pulling codes doing KOER but kept getting codes that only pretained to engine off, which was weird. The last time I tried KEOR was before I replaced the power booster so I do need to try it again just in case but pretty much every sensor I can think of has been replaced in the past 2 years and car is driven maybe 8k a year (thats probably more than it actually driven).

 

[RatStang]

You may need to install a jumper into the Neutral Safety Switch plug that's underneath the car in order to get KOER codes.

I had to do that on my 86.

 

[liljoe07]

The codes need to be listed. Installing the jumper is only if the codes cant be retrieved in the KOER. If the codes were flashed in the KOER test, they are KOER codes.

 

[ebk06]

I cant remember the codes off hand but they were designated are KOEO codes only. I have no idea why they came up with the car running.

Whats this whole jumper in the neutral safety switch?

 

[liljoe07]

Unless one code was a code 67 dont worry about the jumper.

Re-run the codes and post them up. List which ones are KOEO and KOER codes.

Like I said, if the codes flashed with the engine running, they are KOER codes. You can have the same codes in the KOEO and KOER. The meaning of the code may change though. Post them up.

 

[ebk06]

The codes with KOER were codes for the tab and tad solenoids. I dont have any smog equipment in the car so they will always show. No other codes showed up. Also I got a Code 11 during the KOEO.

 

[nos9722]

you still have to set the tps with engine off but the in acc set it to .98v and if the car is idleing high the idle air bypass is bad or it is stuck open to see if you have a vacum leak spray the intake upper and lower and hose with brake clean. if there is a leak the will drop idle then jump back up