I was driving a 10 minute drive, the engine ran great. But I noticed the last 1/4 of the drive, when I stopped at lights my check engine light would come on, flash a bit, turn off and stay off till the next stop. It would do it again. So at the last stop light I stopped far back, and creeped forward and hit the brakes it would come on, and then turn off. Do it again, it would come on, and turn off. It’s not wiring to the CEL it stays solid KOEO. Got home it flashed again stayed solid then turned off. I’m thinking the knock sensor came unplugged?
Tuck does need a new intake manifold gasket, and there is a broken vacuum line going to the coffee can I need to fix. Just haven’t gotten to it yet. Also it hasn’t been pinging
Read KOER codes, these were the DTCs


25 is the only new one. I’ve been driving around with the others. The EVR tested good on OHMS, has power. New EVP sensor. And egr does respond to vacuum and engine will try to die at idle with vacuum applied to the EGR. Not sure how to tell what the different versions of 34 it could be. Not concerned with any except 25 right now, as they haven’t triggered the light. 25 is what I’m worried about since that’s new. I was told these fords use positive back pressure on the egr, and my exhaust leak doesn’t allow for that pressure. But what’s the vacuum line for then? Wouldn’t it be the linear or negative pressure?
Also would it be safe to drive roughly an hour like this?
Can an OBD 1 system even get flashing CEL?

 

so the light flashes when its stopped with foot on brake? Id suspect a bad check valve to your booster and that vacuum line are leaning out your truck or something. You REALLY need to make a signature or include your truck, engine in your posts.

You must have unchecked "add my signature"
Signature1988 Ford F-150 302 v8 AOD 4 speed auto 8.8 rear end 4.10 gear ratio non limited slipi found this "lickering light = bad PCM or intermittent power/ground/short to the PCM essentially causing rapid resets. Since you have tried multiple PCMs, it's a power issue.

The PCM relay and socket is a very common issue on these era vehicles."
does this flashing seem to miimmick the code flashing?

 

What are the KOEO and Stored Codes?

 

I haven’t ever touched the PCM. Is it within reason to take it out and inspect the capacitors etc? It did seem to be mimicking code flashing. Still need to test KOEO, I kept pressing test and it wasn’t doing anything for the KOEO. I heard things clicking when I pressed test but the reader didn’t read. I just got home with food so I decided to do it later. I will update when I can get the KOEO codes. I will look at my signature I keep having problems with it depending if I’m on my phone or computer. It could be when my foots on the brake thinking about it. I’ll inspect the check valve, I have the old one still if the new ones bad. It got replaced with a NAPA one about a year ago.

Edit: now it’s working I haven’t touched the signature yet. I did post this post on the same device as the first post on this thread.

 

test the codes with a paperclip and bypass your code reader in case its not doing what it needs to do

 

I have a O code for 34. I have an 11 for C so that’s good. I’m thinking it’s just the vacuum leaks causing the light. Cause it’s only when I hit the brakes, and that takes vacuum. Maybe my vacuum leaks got worse and now when that happens it takes away vacuum from something else. I need to reseal the upper manifold, and fix the line. But if that’s not the case I still need to pass smog so I have to fix it. I may just disconnect the battery for a bit before I take it for smog, and fix it after.

 

I think youre looking at either a backfeeding of your brake circuit or what I said before. Easy way to find out. Unhook your brake pedal switch and press your brake while running. does the light come on? No ? then it was that. If it does, then we are looking at a more complex issue.

If it does fix it, you can cheat smog by running a switch inline the power to the brake switch, and switch it off when its time to check your light but switch it on to inspect your outside lighting

 

KOEO Code 34: EVP circuit above the closed limit of 0.67 volts.

That could be caused by the EGR valve is not fully seating or the EVP sensor is going bad. Since you are getting Code 34 in both KOE and KOER tests take a close look at the EGR valve for signs of it not fully seating. Verify the EVP output KOEO as well as KOER.

 

My ex-MIL was pretty weird as well, but that's not why I divorced her daughter...