turdle's mounty moves on

[2000StreetRod]

Intake leak

Air must be getting into the intake system somewhere in order for the engine to idle at 2K rpm.

Is the EGR tube connected or open at the elbow? The PCM is supposed to command the EGR valve closed at idle but the EGR vacuum regulator (EVR) may not be working. If you disconnect and plug the vacuum line to the EGR valve it should close unless its stuck open. Also, there should be a manifold vacuum connection to the EVR.

I'm not familiar with the V8 but my V6 has a vacuum line connected to the fuel vapor management valve. If you have one have you connected it?

Did you check the vacuum line to the power brake booster?

 

[CDW6212R]

Those trans codes should be about one problem, hopefully a connector or wires switched/crossed somewhere.

Do check the TPS voltage, just turn the key on and probe the terminals. The IAC should be easy to check, you said it was good before? Those either work or they don't, clean or replace. I'd also look hard for a vacuum issue, even the EGR or PCV system could be contributing to the idle quality.

Which parts are unknown as good to you? How well do you trust the MAF, is it a top brand, or a calibrated POS?

 

[pufferfish]

i only have the EGR stuff, fuel pressure regulator and vacuum gauge hooked up to the manifold right now. all else is plugged. is it possible to have 20" vacuum at 2k with a vacuum leak? how can i check for leaks? i know of the starter fluid sprayed around the gaskets, but is there a safer way?

IAC cant be the problem. i disconnected it and it doesn't drop the RPM. the MAF is a Lightning 90mm. cant say i trust it but also cant say i don't. it did work with the other engine.

i will check to make sure the EGR valve is closed.

i didn't change any of the wires on the harness (which includes the trans), so it cant be a faulty rewire. i will check out connectors tomorrow.

thanks for the info! keep it coming!

 

[Turdle]

I have a few things to throw out/ask

Is the coolant filled and burped? An air pocket in the cooling system will cause high idle. I'm not sure why, but something in the coolant sensor I bet.

Which tune file is being used?

And the cam sensor code. I wonder if a hard failure would cause a limp idle condition? Is there a way to log this?

Do you have the stock oil pressure guage connected, and , does it register pressure?

 

[2000StreetRod]

Lightning MAF sensor

I replaced my stock 55mm MAF sensor with the Lightning 90mm MAF sensor on my SOHC V6. The increase in cross sectional area significantly decreased the speed of the air flow thru the sensor for any given engine speed. Initially I designed and built an amplifier to make the 90mm look like a 55mm to the PCM but couldn't get the gain stable for the large temperature range of the engine compartment. I eventually got James Henson to generate a custom tune.

I don't remember which PCM you're using in the vehicle but the MAF sensor and the PCM tune must match the engine displacement and airflow characteristics. The PCM can adjust to minor changes in intake and exhaust by changing the fuel trims based on the O2 sensor results but only after it goes into closed loop. You now have a custom high flow exhaust and TrickFlow intake system. Your PCM may be staying in open loop and running on programmed parameters.

20 inches of vacuum is not that strong for a long stroke engine with a mild cam. My Haynes book states that an average healthy engine should normally produce about 17 to 22 inches of vacuum with a fairly steady needle.

Are you sure that the throttle plate is closing? Have you disconnected the throttle cable in case it's not adjusted correctly? Is the cruise control cable disconnected?

I have not had very good luck detecting vacuum leaks with aerosols. I've always relied on visual inspection.

 

[pufferfish]

well, i checked the TPS. 0.92 volts at full close. spot on. i checked all the trans connectors. all are plugged in. took the PCV out of the system and plugged the intake connections for it. nothing. i disconnected the vacuum line from the EGR valve. small pulses of vacuum coming from the line. took the EGR tube off the header and checked for vacuum with the engine on. nothing. EGR is now out of the loop and the vacuum line plugged. no improvement. checked everywhere for vacuum leaks. there are none that i can find. checked for vacuum in the crankcase while PCV disconnected. none. throttle plate is full closed. took a hair from my wife and put it in the TB and closed the throttle. it was pinched, so i know for sure it is closing all the way. i checked the alignment of the cam sensor. it was good. unplugged it and started it. no change. i thought that maybe it was 180 out, so i pulled it and rotated the engine once and realigned the cam sensor. no change. coolant is filled. aside from running it, how would one burp it? it has definitely ran enough. i am using the tune that was loaded on when i got the truck. the only difference in hardware is the extra cubes. i spoke with Henson a while back about if the truck would run with the old tune. he said it would.

i just don't get it. i am going to email Henson again to see what he has to say.

 

[Turdle]

Try reversing the IAC mount--just for kicks.

flip it 180. while doing this check if it is stuck open.

Coolant probably will not burp until the thermostat opens.

If possible get the radiator cap higher than the heater core-

 

[pufferfish]

so, i placed a piece of tape over the IAC bypass hole in the throttle body on the outside of the blade. wouldn't ya know it, it won't stay running. i take the tape off and it jumps to 2k. hmmm. i am going to look into this further. i will report back.

 

[Turdle]

Flip the IAC 180 degrees.

 

[pufferfish]

well, it looks like explorer IAC's are oriented opposite of SN95 mustang IAC's. i couldn't flip it around because of the oil fill tube, but a mustang IAC fixed it up. didn't get much time after that, but it didn't seem to have any codes for the minute i ran it. i will get some more time on thursday night to mess with it. hopefully i can take it for a spin

 

[2000StreetRod]

Nice going!

Hopefully your test drive will go well!

 

[Turdle]

Fingers crossed

 

[tmsoko]

well, it looks like explorer IAC's are oriented opposite of SN95 mustang IAC's. i couldn't flip it around because of the oil fill tube, but a mustang IAC fixed it up. didn't get much time after that, but it didn't seem to have any codes for the minute i ran it. i will get some more time on thursday night to mess with it. hopefully i can take it for a spin

Wow - good find! That is valuable infomation for all of us. Good it turned out to be something reasonably easy!

 

[pufferfish]

one note is that the mustang IAC has a different connector than the explorer, but the wiring is the same. i am going to go to a junk yard this week to get the right connector and try to repin it with the explorer wires. if that doesn't work, i will splice it in.

i am suprise the trans issues went away. wonder if the high idle was causing an unexpected high line pressure?

 

[CDW6212R]

Yes, all of that, cross fingers. Good thinking Jon, I have wondered before if the IAC could be flipped around if needed, and still work. Clearly not it seems. Tell the other guy in his high idle thread too.

 

[pufferfish]

yes, thanks jon! you're suggestion saved me ALOT of time! when i got your truck, i wondered why the IAC was flipped backwards (SN95 TB orients the solenoid downstream of the throttle blade). now i know!

so, i planned on going to my local pick-n-pull during lunch today to get a SN95 IAC (the one i uesd was borrowed from my mustang) and connector. i searched anline beforehand to see which vehicles would have the one i needed. seems that the explorer is the norm and the SN95 is the ******* child. i can't find anything but the 94-95 V8 mustang and some SN95 V6 mustangs(not sure which years) with the IAC in this layout. so, off i went. i knew there wouldn't be a gt or cobra there. they don't get the best cars there. but was happy to see a V6 stang with just the right one.

one step closer to the final product!

 

[pufferfish]

well, stonewalled again. had a chance to run it a bit. the same codes keep coming back and it still goes into limp mode. i am going to start with the cam sensor fault. going to verify its set up at TDC of #1 tomorrow night and get a replacement sensor top. i hope that clears that code. after that, i don't know what to do about the trans codes. nothing external is wrong. would i see anything that could be the culprit by pulling the pan?

 

[CDW6212R]

I'd look harder for external issues, it's not likely that many codes would come from one fault inside the trans.

 

[2000StreetRod]

No power to trans solenoids

Your transmission DTCs indicate that there is no power to the solenoids. According to my 2000 wiring diagrams +12 volts comes from the battery junction box fuse 10, thru the PCM power relay, thru fuse 13 in the battery junction box and then C116 pin 3 via a light blue/orange wire and finally to C180 pin 4. Pin 4 is internally connected to the TCC, EPC, SSA and SSB solenoids. I don't have a 97 wiring diagram to see if the wiring is the same as for 2000. I suggest that you make sure the C118 connector is securely connected. If it is then I suggest that you disconnect it, find the pin corresponding to the light blue/orange wire and see if +12 volts is present when the ignition switch is in Run.

 

[2000StreetRod]

Red wires for 1996

I just checked my somewhat limited 1996 wiring diagrams and there are individual red wires that power the four solenoids in the transmission. However, power for them comes from a common source - the PCM power relay in the power distribution box. I believe there were significant powertrain electrical changes in 1998 so your 97 may be more like the 96 than my 2000.