STILL having idle probs, lots -o- work already done and I'm STUMPED

[Huntervf]

Ok, here's the situation: My new 95 ATX won't idle properly when cold. In fact it won't idle at all unless you give it some gas. I've had the car about a week now and I've done a LOT of troubleshooting to no avail. Here's what all I've done so far:

-New IAB
-Removed/disassembled intake & gave it a complete clean, paid special attention to the idle/EGR passages at the neck & they are clean. Seriously, I just spend the weekend on this, you could drink beer through this intake now it's so clean (and I considered doing just that.)
-Reset the idle (after it would idle on it's own anyway)
-Swapped MAF & no change
-Swapped TPS & no change
-Cleaned EGR & no change
-Ran codes numerous times now, here's what I have so far:

KOEO: 543...sometimes this comes up, sometimes it doesn't. I know what it means in memory, but KOEO has me a bit confused as I interprit it to mean the fuel pump isn't cycling, but I hear it running just fine.
565...just got this one today after reinstalling the intake: Canister purge 1 solenoid/circuit failure. What, did I reinstall something wrong? shrug

Memory: Nothing except a rear 02 code, that's getting replaced tuesday (already replaced the front one).

KOER: 412, idle speed too low (duh) and 213, SPOUT circuit open or shorted. Once again, I've only been getting 213 since I reinstalled the intake. Did I forget to plug something back in? Where exactly is this SPOUT circuit anyway?

The intake was quite dirty and one of the IAB/EGR ports near the TB was packed full, the car seems to run stronger and idle does pick up quicker, but it's still low and it still won't idle on it's own.
The other day I put a couple turns on the idle set screw just as a temp fix so the car was more drivable, now after a minute or so of running the car will idle on it's own, but it barely breaks 500 RPM. As the car is driven longer the idle will gradually rise until it hits about 1000, which is where I would expect it to run with the screw dialed up a couple turns.

There are no drivability problems; step on the gas & the car thrusts forward like a healthy SHO. I do occasionally get a CE light but I'm 99% certain it's the remaining rear 02 sensor that I still need to replace.

The idle doesn't bob, fluctuate or stumble, it just runs low and when it's cold/initial startup it doesn't idle at all. It fires right up but then dies back out. Before I turned the idle screw up it would take 5-10 minutes before it would handle 500 RPM, now it only takes 1-2 minutes.

To add to this mystery, I had trouble running a KOER test when I first looked at this car a week ago. I'd get the three flashes and the pulse for the goose test, but after running the test I'd get nothing at all...no flashes of any kind yet the KOEO & memory portion worked just fine. The next day at home I tried the test again and it worked as advertised, and it's been working alright since so I chalked it up to a bad jumper connection since I had a tiny wire vs. my normal paperclip. Now today I ran codes, everything worked just fine but after the goose test I decided to run a cylinder balance test. It wouldn't run it at all and in fact after slightly pressing the gas I got a code 538 indicating the "system did not receive the goose test". shrug I tried this 4 times this evening, and each time I got the same thing. Now I've pulled many sets of codes on many EEC-IV cars and I've done many cylinder balance tests on SHO's: this is the first time I had this happen. Furthermore, the car does NOT idle up at all during the KOER test. Perhaps I have a bad computer after all?

I have an appt. on Tuesday for a tranny flush, front motor mount and new O2 and I'm going to have them check the fuel pressure but I don't see that affecting anything. I'm well and truly stumped on this one and could use all the advice I can get. I'm actually about ready to just take it to a shop shrug

 

[Mr Anonymous]

I probably would have suggested a fuel pressure test before some of the other things you've tried, but in any case that's the logical next step.

FWIW, here's the PC/ED diagnostic routine for a 543 code, maybe it will lead you to the cause:

J20 DIAGNOSTIC TROUBLE CODE (DTC) 543: DOES ENGINE START?
DTC 543 indicates a fuel pump secondary circuit failure between the B(+) supply and the FPM connection to the power-to-pump circuit.

Possible causes:

No Start:

Open circuit between the B(+) supply and the FPM connection to the power-to-pump circuit.
Fuel pump relay contacts always open.
Engine Starts:

HO2S short to power (dual HO2S applications).
Damaged Powertrain Control Module (PCM).
Does the engine start?
Yes No
For dual HO2S applications:
GO to J25 .
All others:
REPLACE PCM. RERUN Quick Test .
GO to J21 .

J21 CHECK FOR B(+) TO FUEL PUMP RELAY
Key off.
Disconnect fuel pump relay.
Measure voltage between B(+) circuit at the fuel pump relay vehicle harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
GO to J22 . VERIFY integrity of fuse/fuse link for B(+) supply to fuel pump relay. If OK, SERVICE open in B(+) circuit. RECONNECT fuel pump relay. RERUN Quick Test .

J22 CHECK POWER-TO-PUMP CIRCUIT CONTINUITY
Key off.
Fuel pump relay disconnected.
Measure resistance between power-to-pump circuit at the fuel pump relay vehicle harness connector and the battery negative post.
Is resistance less than 10.0 ohms?
Yes No
REPLACE fuel pump relay. RERUN Quick Test . SERVICE open in power-to-pump circuit between FPM splice and fuel pump relay. REFER to schematic . RECONNECT fuel pump relay. RERUN Quick Test .

J25 CHECK LEFT/FRONT HEATED OXYGEN SENSOR (HO2S) FOR SHORT TO POWER
Note: Due to the internal circuitry of the PCM, a left/front HO2S signal short to power could produce a DTC 542 or 543.

Key off.
Disconnect left or front HO2S sensor.
Measure resistance between HO2S signal pin and KEY POWER pin at the HO2S sensor connector.
Is resistance greater than 10,000 ohms?

HO2S Connector
Yes No
GO to J26 . REPLACE HO2S. RERUN Quick Test . CLEAR Keep Alive Memory (REFER to Quick Test Appendix, Section 5A ).

J26 CHECK HO2S CIRCUIT FOR SHORT TO POWER
Key off.
Left or front HO2S disconnected.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary. Leave PCM disconnected.
Key on.
Measure voltage between the HO2S signal at the HO2S vehicle harness connector and chassis ground.
Is voltage less than 2.0 volts?

HO2S Vehicle Harness Connector
Yes No
REPLACE PCM. RECONNECT HO2S. RERUN Quick Test . SERVICE short circuit. RECONNECT PCM and HO2S. RERUN Quick Test . CLEAR Keep Alive Memory (REFER to Quick Test Appendix, Section 5A ).

 

[SW SHO]

Now I know why they alwas say "just replace the fuel pump" at the garage....I wouldn't trust a roockie who's never seen SHO, to follow those instructions. Plus all those codes that would have the mechanic suggesting replacing, when not really the culpret. Anyway,

I'm curious, does it idle any better in neutral?

Shooo? Where did you gather those test instructions? For anyone reading this with any say so... I think it good to add stuff like this in link form from the FAQ section. Any takers?

 

[F-22 Raptor SHO]

Well chris......after seeing that Sample tube, I would have said that was the problem.....now I'm in the same state of mind as you: headbang .

I have a spare PCM we can try that. I will drop by with it on Monday.

 

[Huntervf]

IVEYSSHO:
Well chris......after seeing that Sample tube, I would have said that was the problem.....now I'm in the same state of mind as you: headbang .

I have a spare PCM we can try that. I will drop by with it on Monday.

You have a spare computer? Or do you mean the ICM that goes under the plastic piece up front?

Holy **** SHOooo....I can remove/replace parts but if I went through all those steps you can be sure I'd fry something! Thanks for the info though...that gives me a little something extra to go on.

Idle is the same in neutral and park; of course it drops just a bit in gear.