Another Stalling SHO

[DanStp]

My 94 ATX is stalling. I have replaced since last summer the: timing belt, one tensioner, water pump, CPS, alternator, battery, and oil pressure sender, and last but not least the IAB.


It runs fine then will stall. On or off power, sometimes at idle. I ran codes and the code 551 Idle Air Control comes up. I had previously cleaned the old IAB, but that did not help. I then got a new one from Autozone, and still no progress. The 551 code still comes up.

There is one more thing while sitting still and running up the RPM's there is a bad hesitation around 4,000. I assume this something to do with the secondaries in the intake. I have 109,000 miles, and know I am close to another 60k well at least on top. I know I will pulling the intake and changing the wires and plugs to save $$$ myself.

Thanks for any help in advance

<small>[ January 22, 2003, 08:12 PM: Message edited by: DanStp ]</small>

 

[projectSHO89]

Welcome!

Your ATX equipped 94 is SUPPOSED to stutter at 4K rpm while you aren't moving. That's to keep you from blowing up your torque converter. This is not an issue other than understanding that this is normal.

Do you still get the 551 code when running the codes now?

Steve

 

[DanStp]

Yes I still get the 551 code, and it is still stalling, thats the main problem I need to fix.

 

[DanStp]

Just bumping this up in case anyone has any ideas?

 

[AutoSHO]

DanStp:
Just bumping this up in case anyone has any ideas?

Do a search for Idle Speed Reset Procedure and look for a written procedure from sdpatt. Try this before doing anything else.

 

[DanStp]

I have already done that, I did that procedure after cleaning, and also after replacing the IAB. It's not the idle speed that is bad, it is the fact the car will stall anytime it feels like it cares to

 

[rangerj]

DANSTP,

I have a theary on what might be causing your problem. I had this happen on another brand of vehicle. The the system is comparable to the SHO's (more or less, both systems are before OBDII).

The throttle position sensor sends a signal to the computer with a range of approximately .3 volts to 5 volts. As long as the signal is within that range the computer will not code.

However, lets say that when you are at about 1/3 throttle, but the TPS is sending 4.9 volts to the computer. The computer thinks that you are at or near wide open throttle, and tells the injectors to pour in the fuel.

The O-2 sensors detect the rich mixture, and the computer blames the IAB (codes) because its "step" setting is believed to be on the low side. I spent a long time watching the "real" time sensor values, and finally replaced the TPS. Everything went back to normal.

Steve, Terry, SDPATT, please jump in here with your experiences. Could this happen with the SHO system? This is one we can all learn from. rangerj

 

[DanStp]

Well here is the update on my situation. It just quit stalling!! I will test it out more thourghly this weekend, but I took it to a shop today, and it ran the 30 miles down there perfectly? He drove it around and said it ran like a top, he and a couple of other employees took test drives, and it would not fail.

His theory is that the Ford computer takes a lot of time sometimes to reset itself. And, that the 40 to 50 miles I had driven after replacing the IAB had not reset the computer?

I don't know guys, but I will pick the car up in the AM and report to the forum what happens after a weekend of testing.

 

[DanStp]

Well that was quick, once it got warmed up, it started stalling about 10 minutes away from the shop. The check engine light came on briefly during one spell. I guess it's back to the shop on Monday AM. If anyone has anymore ideas I would love to hear them. I will run that last one about the TPS etc by the mechanic.

 

[rangerj]

DANStP,

If your Check Engine light came on there should be a code. Check to see what if any code was stored in the computer.

When you go back to the mechanic have him/her scan the sensors in real time, that is while the engine is running. Check the values or information you are getting from the sensors against reality.

For example, is the coolant temperature sensor telling the computer that the coolant is 72 degrees, but the engine is fully warmed up! Is the Throttle position sensor indicating a higher voltage than it should at idle, but not more than the 5 volt max.

The problem you are having would seem to be either an intermittently failing sensor, or a poor connection or ground in the circuit that is coding.

When the problem is discovered and repaired, please update us on the results. This is a common thing with many of our cars. LOL rangerj thumbs_u

 

[DanStp]

Well here is the latest folks.
I replaced the TPS, figured it was easy to do, and cheap. No Effect Back to the shop on Monday, if anyone has any more suggestions I will pass them along to the mechanics. Thanks in advance

 

[93EmeraldMTX]

My SHO has an idle problum as well. The first few times I started it this winter, it would not idle, and id end up having to keep it running myself until it got warm enough to idle. I got tired of that, and moved the idle screw a little bit, now it idles when cold, but once it fully warmed up it idles at about 1,200 RPMs. Any ideas?

 

[91 Plus]

My car is doing same EXACT thing!i am gonna go run the codes now! there is a act sensor i think its called that goes into the side of the air box! that code came up for me before but i am going to double check the codes..i will post later on when i return!

 

[DanStp]

Well here is the latest update. SHO is dead on the side of the road, and will not start. Is this progress? LOL It is going back to the shop on a flatbed, hopefully they will find something wrong with it this time?

 

[DanStp]

My SHO is back running good
My mechanic was finally able to get to it, and it was a combination of bad grounds in the wiring system, and he replaced the ignition module on the intake manifold Thanks for all the help guys. I think this shows you can believe what the SHO's computer is telling you?
It's so nice to feel it run smooth and just right again.