Intermittent CEL light

blue94sc

Registered User
Recently I have been getting an intermittent CEL light at partial throttle.
I don't get any KOEO or KOER codes but i do get three codes from continuous memory of 181, 185 and 189 stating both banks running lean and the Mass Air Flow lower than expected. I have replaced the fuel pump recently with a Walbro 255lph. I have also replaced the TPS with another one to see if my old one had a dead spot in it. Sometimes it hesitates during the transition between vacuum and boost. And sometimes it falls on it's face when I stomp on it. It used to burn the tires but it lags until aroung 2500 rpms then takes off. I also used to get a little spark knock but that has disappeared. (weird)
This weekend I plan on installing a new fuel pressure regulator and possibly an older style blower pulley and raised top. The center catalytic converter has been gutted and seemed to make a little difference. I am currently in the market for an aftermarket exhaust and plan on a tune as well.
Does anyone have any ideas of where to check?
My vacuum looks good and I have tested the prone areas with no signs of a vacuum leak. Autolite plugs and Taylor wires were in stalled this past winter also.
Stumped..
 
When was the last time the O2s have been changed? They could be the cause of the lean condition and could be triggering the MAF code as well. To save yourself some time and money if you have a spare MAF laying around you could swap them and see if that fixes your problem otherwise new O2s are not that expensive to replace.

Shane
 
blue94sc said:
Recently I have been getting an intermittent CEL light at partial throttle.
I don't get any KOEO or KOER codes but i do get three codes from continuous memory of 181, 185 and 189 stating both banks running lean and the Mass Air Flow lower than expected. I have replaced the fuel pump recently with a Walbro 255lph. I have also replaced the TPS with another one to see if my old one had a dead spot in it. Sometimes it hesitates during the transition between vacuum and boost. And sometimes it falls on it's face when I stomp on it. It used to burn the tires but it lags until aroung 2500 rpms then takes off. I also used to get a little spark knock but that has disappeared. (weird)
This weekend I plan on installing a new fuel pressure regulator and possibly an older style blower pulley and raised top. The center catalytic converter has been gutted and seemed to make a little difference. I am currently in the market for an aftermarket exhaust and plan on a tune as well.
Does anyone have any ideas of where to check?
My vacuum looks good and I have tested the prone areas with no signs of a vacuum leak. Autolite plugs and Taylor wires were in stalled this past winter also.
Stumped..

My car did the same thing....turned out to be a fuel pressure problem. Yours could be the fuel filter or the pressure regulator.

David
 
Busy weekend

Thanx guys.
I plan on replacing my fuel pressure regulator this weekend along with seeing if I can gut the front cats. One has a rattle and I think that is is broken. Last night I cleaned my MAF wires and checked to see if the TB was sticking. Today it was running pretty decent but is still a little weak in the low end.
I will also replace my temp sender. I have already replaced the ACT sensor when I was getting spark knock. Since I will have the blower off I will pull the plugs and check the gap and their condition.
I just might replace the O2's since they are original and at 150k miles.
Thanx again David & Shane.
Bill
 
blue94sc said:
Thanx guys....
I just might replace the O2's since they are original and at 150k miles.
Thanx again David & Shane.
Bill

Bill,

Ouch! :eek: 150K on original O2's. Pretty sure O2 usually last up to 100K miles before they go bad. I would bet they could be a good portion of your problem.

Shane
 
Much better!

Wow! After pulling out my hair for a week I changed both O2's and she woke back up again.
No more CEL and the power has returned.
Its put the ooooo back in my soooper coooope!
Now back to smoking the ricers. Hehe.
Thanx a lot for the tip Shane.
Bill
 
What Are CONTINUOUS MEMORY Codes?

My '94 continues to run bad but I have no KOEO or KOER codes. I have a ACTRON code reader but the car always passes. Like Bill I have the intermittent CEL primarily when I'm crusing about 40 MPH going up a hill. All other times I have no CEL. How do I read CONTINUOUS MEMORY codes? Can I do it with my ACTRON or is there some other trick or code reader I need. If I could get those codes, I believe I could finally solve my year long problem.

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36 lbs Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, 190 l/h Fuel Pump, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, Accel 36# injectors, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, MSD DIS-4 Ignition Box with Tach Adapters, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
Continuous memory codes

Hey Ed.
The continuous memory is read during the KOEO (key on engine off) test.
They will be displayed in the second half.
My KOEO reading was displayed like such;

111
(pause)
111
-------- (single blink)
181 (lean right side)
185 (MAF lower than expected)
189 (lean left side)
(Pause)
181
185
189

The codes will repeat themselves twice with the on demand memory then seperated by a single blink/beep, then the continuous memory.
I too have the Actron scanner.
So far after changing the O2's I have had no CEL light.
Hope you get your SC straightened out as well.
LMK if you need any more info.
Good luck Ed.
Bill
 
It's Baaaaack!!

The intermittent CEL light has returned. I replaced BOTH O2 sensors less than a month ago and it lit back up again Friday on my way home from work.
The continuous memory said 181, 185, & 189. These are the same codes I was getting eariler. I cleared these codes and tried to get it to come on again.
Sure enough tonight on my way home it lit up again and went off. This time I only got the 181 & 189 codes (right and left bank lean part throttle).
Somewhere I read that another person had the same trouble after 5k on new O2's.
The one's I purchase were Bosch. Are Bosch O2's good or bad?
My vacuum is good and I am not getting any spark knock.
I have a new FPR from NAPA (Echlin) to replace my original with 150k.
Does anyone have any other ideas? I did clean my MAF wires to make sure thay werent the cause.
I about ready to begin replacing ALL of the sensors that are original.
I am losing what little hair I have left.
DOH!!
Bill
 
Sounds like a screwey MAF to me. Even though you cleaned it, perhaps it has a problem or maybe the 4 wire connector is corroded.

HINT. I used a S/C MAF on a 4.0L Exporer. You need to carefully dissasemble the 4 wire harness and switch 2 wires to match the pattern up.

My buddy had a 4.0L Ranger MAF go bad......he had the same symptoms as you. CE light on and off.....ran like crap.

I think most Ford MAF sensors will fit.......although the housing are different, some of the sensors are common amongst other Ford's. The part number is designated by the second group of #'s Example... E9SF-3YHH8-AA The 3YHH8 would be the MAF part#. Have seen MAF's with different wire heights, but essentially they all do the exact same thing.

Another trick I learned to. DIS Coil packs are swappable. There are four wires that go to the coil pack. One is power, the other three are triggers that fire each of the 3 coils. The trigger pattern is different from the 4.0L to the 3.8L S/C. We changed the Explorers wire harness to match the S/C's trigger pattern and the truck fired right up. We were trying to trouble shoot a bad running problem that eventually turned out to be upper intake gaskets.

To swap wires in the harness, use a 90 degree dentist pick, and carefuly pull out the rubber seal where the wires go into the hard plastic connector. Then use a real small flat screwdriver and from the connector end, release the small plastic tab that holds the blade connector and pull the wire out of the harness. They simply click back in. No sense cutting them and making a mess. Just be sure to make notes in case you ever want to swap something back.
 
Check the connection

Thanx for the insight.
I never though of checking the connection.
The MAF on the car is a modified MAF (MN12 Performance tip). I am going to throw on my original housing to see if the light comes back on.
Thanx again.
Bill
 
Modified MAF bad

Bingo! It was the MAF all along.
Swapped out the modified MAF with my original stock one and no more light.
Does anyone know any technical info on MAF's?
Is the sample tube on a 70mm smaller than a 76mm MAF?
I always wondered what the relationship between the sample tube and MAF size was.
Thanx for all the help!
Bill
 
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