Erratic idle and stalling at stops

Traakon

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Mar 22, 2015
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Queen Creek, Az.
Hey Y'all

Well, for 2 months "OSO" has been running better than at any time since we owned her. The major issue with stalling seemed to be resolved with the TPS replacement (after 4 months of replacing everything else), the new O2's relocated in the new custom '96/'93 cat-exhaust system resolved other drive-ability bugs and other than the EGR code (which I have given up on) all was wonderful. Guess no good thing lasts forever.

New symptom - Starts fine, idles high as usual for short time then once it drops off and would normally go into the 600 rpm idle it acts like it is confused. It will almost stall, then run up to 8-900 rpm then drop and almost stall. If you add driver input it will run and drive fine until you come to a stop or slow significantly then it will start the whole "chase the rpm needle" game and stall.

I have checked for bad/disconnected/open vacuum lines and found none. I pulled and cleaned the PCV valve with carb clean (also ordered a replacement) and this had no effect. It's not throwing any new CEL's so I have no direction indicated there.

My wife says she (the 'cruiser) is just jealous that I have started spending more attention on the '71 Lincoln and is acting out. Oh if that were just true :)

Any thoughts on what direction to take with this would be appreciated.
 

ajax1

 
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Feb 7, 2009
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2,177
Unplug the iac while running should make idle bounce all over
 

Traakon

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Mar 22, 2015
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Location
Queen Creek, Az.
Unplug the iac while running should make idle bounce all over
LOL...based on the symptoms how would I notice the difference.

Even though it metered with the 20-30 ohm spec's I did pull it and clean it thoroughly. At 350.00 it's not a part I would replace just on suspicion like some others in the past.
 

Traakon

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Mar 22, 2015
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248
Location
Queen Creek, Az.
Is your egr sticking, you can get rid of it on 93 and 94
I have replaced all the parts in the EGR system, checked and rechecked and rechedrechecked the wiring and after 2-3 days of running up pops a fresh EGR CEL. I am on the verge of just jumpering it out but I hate NOT FIXING something. I don't like mysteries.
 

ajax1

 
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Feb 7, 2009
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93 should already have the plug short you don't have the temp sensor correct?
 

MDarius

I break stuff.
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IAC = idle Air Control? Something else? Is it the same part on a 95? If it is I'd be happy to send you mine so you can at least test to see if this is it. If it is you can buy it from me on the cheap or send it back and buy a new one. Just send me a picture and location so I know what to pull.
 

Traakon

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Mar 22, 2015
Messages
248
Location
Queen Creek, Az.
IAC = idle Air Control? Something else? Is it the same part on a 95? If it is I'd be happy to send you mine so you can at least test to see if this is it. If it is you can buy it from me on the cheap or send it back and buy a new one. Just send me a picture and location so I know what to pull.
Yes, Idle Air Control.
According to the FSM the one I have is just fine. It tests out within spec's. I appreciate the offer, if I get something else leading me down that path again I may be in touch.
 

MDarius

I break stuff.
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Well, whatever you need. I've got a 95 with most parts still in tact. If I can help you troubleshoot it by sending some test parts your way I'm happy to do it. These mysteries can get pretty frustrating.
 

Traakon

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Mar 22, 2015
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Queen Creek, Az.
93 should already have the plug short you don't have the temp sensor correct?
By "Jumping it out" I meant a full EGR delete but I have taken great pains to keep the emissions equipment intact on this, if not for me here in AZ but for any future owner. It I decide to send this to a new home someday I don't want the new owner to be trying to figure out how all the stuff was bodged or deleted. That's why I have left it go until I figure out what's causing the CEL.

The focus of this thread is something that I need to resolve just to make it safe to drive.
 

Traakon

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Mar 22, 2015
Messages
248
Location
Queen Creek, Az.
Well, whatever you need. I've got a 95 with most parts still in tact. If I can help you troubleshoot it by sending some test parts your way I'm happy to do it. These mysteries can get pretty frustrating.
I did some digging and the '95 has a different PN (22270-66011) than the one for '93 (22270-66010). I am not sure what the difference is other than the PN for the '95 sells for half what the '93 PN goes for.
 

Traakon

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Mar 22, 2015
Messages
248
Location
Queen Creek, Az.
Well replaced:
PN 12261-66020 and 12262-66020, vent lines
PN 12204-35040 PCV

PN 90480-18001 PCV Grommet

This appeared to have no effect on the symptoms but since the vent lines were both so rigid they broke when bent they were in need of replacing on "just cause".
Pulled the Idle Air Control again just to run it through the powered test cycles (the motor coils metered properly in the resistance test) and it seemed to cycle through each step as the FSM indicated.
In more digging I found some posts that indicated the Coolant Temp Sensor can also cause some of these same symptoms so I have one on order as well as a new Power Brake Booster check valve, grommet and line. It seems that a vacuum leak in that direction can also cause some similar symptoms. The grommet is loose and rock hard as is the line so more items on the "Just Cause" list even if they ultimately have no effect here...guess I will find out soon.

The wife took it to work yesterday (she works from home but does have to trek to the office occasionally) and got lightly clipped as it stalled while making a left on to the freeway ramp. The guy behind was "talking on his phone" and when the 'crusier suddenly slowed he did not and swerved and grazed the right rear bumper. Just a scuff but if I can't resolve this soon I will have to have her stop driving it at all.

 

ajax1

 
Joined
Feb 7, 2009
Messages
2,177
Have you checked the relays? Change the circuit opening one it controls fuel pump on off and I'd also do the main efi relay
 

Traakon

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Mar 22, 2015
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248
Location
Queen Creek, Az.
Have you checked the relays? Change the circuit opening one it controls fuel pump on off and I'd also do the main efi relay
The fuel pump relay and the fuel pump resistor were changed when I replaced the fuel pump chasing the last issues I had. (Along with the ECM, the AFM, and the TPS.)
I have not changed the EFI relay. What would be the corollary with the current symptoms?
 

ajax1

 
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Feb 7, 2009
Messages
2,177
Circuit open relay controls on off of fuel pump
Fuel pump relay and resistor control the speed and voltage of the pump
Change the big efi relay also you can do both the relays I've mentioned for 20 bucks or so
 

ajax1

 
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Feb 7, 2009
Messages
2,177
Well if your pump is turning off and on you would be stalling
 
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