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Topic: Fixed-->trouble shooting check engine light--codes (Read 1823 times) previous topic - next topic

Fixed-->trouble shooting check engine light--codes

Hi all,

I am trying to get my 88 turbo coupe ready/registered for spring.  It has 221k miles (mostly highway as a daily driver for the past few years), the 5 speed shifts smoothly and the car has plenty of power.  The car runs great and fuel mileage is excellent, but my check engine light is on.  The only symptom is a *slight* hesitation when first starting, but this would be un-noticeable for those who didn't know the car.  The check engine light goes off, then comes on/stays on after a few seconds.

KOEO test gave error 22 (BARO out of range).

KOER test gave error 22 and error 34 (EGR did not respond).

I replaced the BARO sensor and the EGR valve with new ones and still have the error.  My hunch is that the EGR/EVP sensor may be at fault, but I haven't checked it yet.  I don't want to replace parts needlessly, but I need to get the CEL to go off so I can get the car registered.

Any advice on which direction to turn/what to try next?

Daniel

Fixed-->trouble shooting check engine light--codes

Reply #1 –
Hey Daniel

Do you have greenish/yellow and black valve hanging off the EGR vac port? Also look for a sticker under the hood indicating the EGR has been modified and may cause code 34. The reality is the TC EGR is very crude and will almost always throw a code when doing the KOER test.

Your CEL is a hard fault.... i dont have the codes in front of me but that code 22 BAP fault is likely the problem if there are no other codes. Here is very good write up for testing,
http://sbftech.com/index.php?topic=19336.0

John

Fixed-->trouble shooting check engine light--codes

Reply #2 –
Thanks, John. I'll see if I can get a frequency tester. I left most of my tools out west when I moved east, so will have to get a replacement...

I do have the greenish/yellow and black valve in the vacuum line in series just after the EGR.  This functions as an anti-siphon valve, yes?

Daneil

Fixed-->trouble shooting check engine light--codes

Reply #3 –
It is a vacuum delay valve. Something left over from the carburetor days. Ford decided to add the valve as part of a recall or TSB ..... I can't remember but they also replaced the catalytic converter at this time. The valve basically delays the vacuum signal to the EGR valve for around 2 minutes rendering it non-functional unless you can maintain a steady state cruise long enough to allow the signal to open the valve.

Lol.....Guess this was a loophole for emissions requirements. They didn't disable or remove it.....Just delayed it's function long enough to keep it from opening.

John

Fixed-->trouble shooting check engine light--codes

Reply #4 –
The Turbo engine doesn't have an EGR Valve Position (EVP) sensor. The test opens the EGR valve at idle and expects the idle rpm to drop.
Try removing the delay/check valve in the vacuum line and connect vacuum to EGR without the check valve.

Fixed-->trouble shooting check engine light--codes

Reply #5 –
I always removed the vac delay and tossed them, as mentioned was part of recall wasn't originally installed.. BUT I've never seen one that caused a CEL, though they do set a code ... I can see that happening if it didn't allow EGR to open at all, but apparently the delay was short enough in duration not to do so...

Fixed-->trouble shooting check engine light--codes

Reply #6 –
Found the Recall TSB that installed the vacuum delay. They should have wrapped this label around the test connector:

Fixed-->trouble shooting check engine light--codes

Reply #7 –
Thanks for the TSB copy.  I don't remember seeing that one.  I hope to work on the car a bit this weekend and will provide an update.

Daniel

Fixed-->trouble shooting check engine light--codes

Reply #8 –
Well, after a lot of buttstuffysis and testing, it appears it is the computer that is being troublesome.  I'm replacing the computer with one I know is good in order to confirm the diagnosis.  I'm also going to double check the connections to the EEC-IV.  Over time these may work loose.

Right now I'm replacing the rear brakes and lines in order to pass the safety inspection. One of the lines going into a caliper was leaking. :(

Oh well.  The car should be ready for spring soon.
 

Fixed-->trouble shooting check engine light--codes

Reply #9 –
I replaced the computer with a good one and solved the check engine light issue.  Thanks for all your advice and help.  While I was at it, I had to replace the rear calipers/rotors/hoses and fix a separated window.  The car should be ready for spring now. :D

Daniel