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4 blinks from check engine light


MT-2500
01-12-2011, 06:47 AM
94 F-150 5.0 - V8 AT 2W 149K on clock.
Engine starts and the shuts off when cold.
Restart and runs good the rest of the day.
But when started the check engine light blink 4 even blinks.

About 2 weeks ago I check computer system and found a bad TPS sensor.
Replaced it and all test good.
Customer try ed it out and said it ran better but still had the dye on start up and 4 blinks from check engine light.

He brought it back Monday and asked for another check out.
This time the MAF sensor was dead with code 157-158 for MAF sensor and 172 for 02 sensor.
It set code for not switching and would blink light one time on road test when code set on road test.
Also had code for transmission tempt sensor.

Replaced MAF sensor and O2 sensor.
Runs good and not setting any codes now.
Even cleared the transmission sensor code for some reason unknown.

But.
Engine starts and runs better with less dye out but still get the 4 blinks from check engine light.

Thanks for any info.
MT

danielsatur
01-12-2011, 03:12 PM
Did you reset the codes?
A bad performing engine could give false symptoms to a good transmission.
New -MAF and O2 sensors.
How old are the plugs & wires?
How old is the Air/fuel filters?

Doing regular routine maintenance can weed out most problems, befor they happen.

MT-2500
01-12-2011, 03:32 PM
Did you reset the codes?
A bad performing engine could give false symptoms to a good transmission.
New -MAF and O2 sensors.
How old are the plugs & wires?
How old is the Air/fuel filters?

Doing regular routine maintenance can weed out most problems, befor they happen.
Thanks for the info.
Yes MAF sensor and 02 sensor repaced.
Tps sensor replaced a couple of weeks ago was setting code for TPS
Yes codes cleared after MAF sensor and 02 sensor replacement yesterday and road tested retested and no codes return.
Not even transmission tempture sensor codes has returned.
Plugs and wire and cap and filters have very low mileage on them
Only thing I noticed on road test is engine tempt has a a 13 degree range when going down road or setting still running.
Range from 183 -196 degrees back and forth ever 3-4 minutes.

One thing I discovered with scanner plugged in the engine light does not come on key on but does blink 4 times on start up.
Unplug scanner and engine light on key on and goes out start up with no blinks.

Will restart cold in mooring with scanner off and see if no dying out and if it has still has the 4 blink deal on start up.
Dang 4 blinks on start up cold is driving me nuts.
Thanks
MT

way2old
01-12-2011, 07:21 PM
By any chance does the DLC have any crud or a possible short in the wiring? It sounds like the EEC IV system may be trying to keep checking itself and it is flashing the light 4 times for the 8 cylinder engine. Years ago I ran into one where a person had left a jumper wire in the DLC and caused a similar problem. Mine was on a Taurus and it flashed 3 times. Just a thought.

MT-2500
01-13-2011, 07:54 AM
Hello Way2old
Long time no see.
Glad to hear from you.
Thanks for the info.

Good idea on the short wiring on diagnostic connector.
Them things do get in bad shape and corroded up bad.
For should put them inside like GM.:rofl:

Yes I did look it over and I discovered the 4 flashes on start up is the computer checking itself because of a problem it was picking up.
The last check I found a shorted MAF sensor and bad 02 sensor.
A couple of weeks before that it had a bad TPS sensor.

After replacing the MAf and 02 sensor and clearing codes and retesting I left my scanner turned off but hooked up.
I unplugged it and no more 4 flashes on start up.

Left truck outside last night and on start up this mooring no more 4 flashes.
But did dye one time on start up.
May need drove some more so it can fully reset itself.

Changed stat but still getting function on engine temperature.

Going to road test some more to day.
Customer wants it to start and run with no dye out of a mooring.
Good customer but he wants it running right.

Thanks for info.
MT.

way2old
01-13-2011, 07:16 PM
Does it die almost immediately, or does it idle for a little bit? Have you cleaned the throttle body lately? Possibly the IAC hanging. GTuess you got to CRUNCH some PIDS to find answer. I will keep thinking also.

danielsatur
01-13-2011, 07:58 PM
Is the Incoming Air Control Temp (IACT) sensor located on the MAF ?
The MAF sensor was replaced, but was the IACT.

The IACT signal is used by ECU/PCU, so it can set the fuel pulse!

MT-2500
01-14-2011, 07:45 AM
Does it die almost immediately, or does it idle for a little bit? Have you cleaned the throttle body lately? Possibly the IAC hanging. GTuess you got to CRUNCH some PIDS to find answer. I will keep thinking also.

Yes Crunch and check and recheck.:rofl:

Yes yesterday moring on a cold start died right after cold start.
Restarted and ran ok.
This moring I gave the key on 2 time to prime fuel pressure good and no die out and no 4 blinks.

Throttle body has been cleaned several weeks ago with TPS sensor replacement.
But engine is sucking some oil from engine vent threw the intake hoses and putting some oil in throttle body.
Not good for IAC valves and may be what knocked out TPS sensor.

Replaced thermostat but still getting a big fluncation on engine temptur going down road.
Truck has a bigger radiator replacement and water pump is almost new.
Before stat replaced tempt was going from 196-183 degrees ever 3-4 minutes.
After stat replacement 209- 186 ever 3-4 minutes on road.
Tempt gauge and computer tempture readings both.
But was tested with outside tempture about 10 degrees on road.
Will drive again today and see how that end does.

Thanks MT

MT-2500
01-14-2011, 07:52 AM
Is the Incoming Air Control Temp (IACT) sensor located on the MAF ?
The MAF sensor was replaced, but was the IACT.

The IACT signal is used by ECU/PCU, so it can set the fuel pulse!

Intake air tempt sensor is in air intake hoses at air filter.
I have not checked it real close but will read it out good today on cold start and warm up and hot on road.
Tempt here has been cold around 10 degrees,
Good time to check IAT out.
Looks like that the MAF sensor and 02 sensor fixed the 4 blinks.
And no die out on start up this moring.
Thanks for the info.
MT

MT-2500
01-23-2011, 08:47 AM
Well that fix went to pot.
I thought it was fixed.
Customer came and got it.

He drove it for about a week and it was still acting up on start up.
Dying some and a blink or two and check engine light come on some.
Then running good.
So he drove it on a 100 mile trip to his medical center.
On the way it almost quit running and had fits.

When he got there he took it to the ford dealer there.
They said MAF sensor code.
They did not have one in stock so they unplugged it so he could drive it back home.

Customer call me and told what they had done and that he wanter a Ford OEM Maf sensor over the aftermarket that I had installed.
I order it and it came in a ford rebuilt.

Customer brought it out yesterday so I installed the ford MAF sensor and plugged it up and hooked up scanner to clear codes and get a read out on computer sensors.

My old MT-2500 or New solars Pro scanner acted strange.
Would not read out codes or clear codes but did give data reading.
Maf sensor reading checked out good.
Customer drove up road for road test and came right back.
Truck having fits.

Hooked scanner back up and noticed the Maf sensor reading had reset to or dropped down to the 26.4 baro range from the 29.8 reading.

Also the new 02 sensor reading was hitting over 1.111 1.200 and not fluting just holding steady and not much closed loop operation.

I have a strange feeling that the computer is going bonkers.
But will try another 02 sensor first.

MT-2500
02-27-2011, 10:50 AM
After computer replaced 1 time and tps and maf sensor and 02 sensor replaces 2 times.
Still not fixed.
Last problem find was engine coolant had seaped into front 02 sensor plugin and damaged it.

Rewired around it and still not fixed.
Cold start up get the 4 blinks and engine dye out.
The warmer weraher is making it better but not all fixed

When cold shows code for tps sensorn and transmission coolant sensor.
After warm up they leave.
Engine runs good outside of having few fits of coughing and jerking
But get a merryround of other codes.
Sometimes tps sensor code 02 sensor.

After telling Customer about the 02 sensor plug in being bad he got to looking at the wiring to it beside battery andn looks like battery acid has run down into the4 battery cable and 02 sensor wires going from side of battery to starter.

He went to pull it bone yard and found a 02 sensor wiring for 1$
I will install it and see what it does.

Still open for any ideas or suggestions or help.
Thanks MT-2500
PS
I have noticed on scanner the tps sensor voltage going up and down with key on engine off.

And A time or two it has went to 0 voltage and throwed TPS code.

olopezm
02-27-2011, 03:25 PM
The voltage fluctuation can be caused by either a bad ground or a bad alternator, I would inspect for both, maybe a diode is shorting to ground and that can cause lots of electrical gremlins.

Just my opinion...

Best regards,

Oscar.

MT-2500
02-27-2011, 04:30 PM
The voltage fluctuation can be caused by either a bad ground or a bad alternator, I would inspect for both, maybe a diode is shorting to ground and that can cause lots of electrical gremlins.

Just my opinion...

Best regards,


Oscar.

Thanks.
I will check into that end .

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