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Again, multiple codes, car runs perfectly. by RayOtton
Started on: 10-09-2014 03:15 PM
Replies: 6 (90 views)
Last post by: RayOtton on 10-10-2014 06:11 AM
RayOtton
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Report this Post10-09-2014 03:15 PM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I posted a few weeks back about this problem. '88 Formula, automatic with the following mods:

1 - Ported exhaust
2 - Ported Y-pipe
3 - Streetfire coil
4 - Ported UIM
5 - 56mm throttle body
6 - Low restriction cat
7 - Underdrive pulley
8 - 11 degrees initial timing.

The consensus was a possible voltage regulator problem. Took it to the shop that put in a new alternator about 1K miles ago. They decided to replace the alternator at no charge.

Now rather than eight codes I have 14!

Service engine light comes on after about 5 minutes of driving. Shut it off and turn it back on and after about 5 minute it comes on again.

Here's the codes:

12 - No distributor signal
14 - Coolant sensor
22 - TPS low volts
24 - VSS open or shorted
33- MAP sensor volts low
34- MAP sensor volts high
35 - IAC cannot set idle
42 - Electronic spark timing open
44 - Lean exhaust
45 - Rich exhaust
51 - ECM failure
52 - ECM fault
54 - Fuel pump circuit fail
55 - ECM fail or Ox sensor fault.

As I posted last time, the car is running great. Start easy, idles smooth, plenty of pep, no exhaust smoke and the MPG hasn't changed.

Something else wrong?

I mean, should the car be running at all, let alone purring, with this many codes?

Time to remove the "Service engine" bulb and just enjoy the ride?
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Gall757
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Report this Post10-09-2014 03:26 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
The ECM is having trouble of some sort. I would disconnect the reset connector near the battery and let is start over. It could be internal, or a bad connection somewhere. I wonder if your aftermarket coil could be sending junk voltages back to the ECM?

[This message has been edited by Gall757 (edited 10-09-2014).]

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Alex.07.86GT
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Report this Post10-09-2014 04:21 PM Click Here to See the Profile for Alex.07.86GTSend a Private Message to Alex.07.86GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

The ECM is having trouble of some sort. I would disconnect the reset connector near the battery and let is start over. It could be internal, or a bad connection somewhere. I wonder if your aftermarket coil could be sending junk voltages back to the ECM?




nice pic!!

Thanks!!
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RayOtton
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Report this Post10-09-2014 05:47 PM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
First, thanks for the picture, that took some effort and I appreciate it.

I will try that reset but could you elaborate on the procedure? Is it a simple disconnect / reconnect?

FWIW, the aftermarket coil has been in the car for about 6 months. The service engine light didn't start coming on until about two months ago after the last mod, which was the 56mm throttle body.

A related question comes to mind.

Is there a "limp mode" in the ECM and could I be running in that mode now? If so, what exactly is it?
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Gall757
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Report this Post10-09-2014 05:56 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
First off.....Thanks should go to the Ogre for his marvelous Cave....He made the photo years ago. Spending time in the Ogre's Cave is the quickest way to get smart about Fieros.

second.....The reset connector is just that...most recommend that you wait about a minute before re-connecting.

Third.....there is a de-facto limp mode in the computer....if it gets scrambled it reverts to a default on many of the settings.. If the throttle body was the last mod before trouble, I would examine the TPS....maybe there is a short in that connector, or maybe your new throttle body is too much for the TPS to deal with.....

[This message has been edited by Gall757 (edited 10-09-2014).]

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fierofool
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Report this Post10-09-2014 06:06 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Limp mode will show rapid flashes of the Service Engine warning light. With the SES light not coming on until after you've driven it a short distance at road speeds would generally indicate an EGR system fault, Coder 32. The light will go off when the ignition is turned off, only to return when you again drive at road speeds for a short time. Oddly, that's not in your list. I would suspect a faulty ECM. Maybe even the wrong ECM. A local Fiero owner recently found a Camaro ECM mounted in an 86SE. It had the same harness connections and appeared the same as the Fiero ECM. Since it was a car acquired for parts, though it would start and run, it was never driven on the roadway to register any trouble codes.
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RayOtton
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Report this Post10-10-2014 06:11 AM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you for the replies.

I will try the ECM reset procedure but the thing is, since it's not in limp mode ( service light not flashing ) and multiple codes indicate an possible ECM problem, then how the heck is the car running so well?

Could the cumulative addition of all the mods caused this?

Of course, I'm not the first guy here to put these mods in place so why hasn't this problem surfaced before if it's just the ECM not being able to handle the modifications?

Also, would a modified chip from one of the members here be the answer?
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