Problem with -89 Bronco 5.0. Check engine light flashes irregularly while accelerating. Engine has lack of power and knocks easily in uphills.
No fault codes on koeo test, only 11. Ingnition timing is 10 degrees.

Does anybody have suggestions where problem could be?

 

Run a KOER test. The issue is lost in the dynamics of the engine performance. KOEO test will only get you what is stored in computer memory.

 

Koer test: 11, system pas. What next? Kan it be egr or airpump related problem?

 

Sounds to me like a miss or crossfire. I forget firing order for the 50, but the wires that fire one after another (2 and 3, for example) make sure they aren't touching at all.

I can get minor crossfires where it's just an occasional stumble, misfires from wires grounding on the block, etc.. but the absolute worst I ever had it was when my 7 and 8 wires were crossed/wrapped around each other, I got a loud BAM, BAM, BAM when I put my foot into the throttle and a flashing check engine light.


and IMHO you need to do the CM test..

CM will show memory of stuff that has happened, KOER only shows what is happening when the tests are running, KOEO shows unplugged or completely non-functional sensors or components, like if they have a short.. but then again, even though I'm almost completely sure on this, I don't like saying different than greystreak because he's usually right.

 

I also suggest the CM, Continuous Memory code check. Wires to separate for cross firing will be either 7-8 or 6-5 firing sequentially. Just turning a wire boot on the distributor made a difference on mine. Of course, good wires, cap, rotor and copper plugs should be mentioned. Doesn't the 5.0 have a knock sensor and is it functional? My credibility may be sacrificed with this statement, I am trying NGK V-Groove copper plugs and like them so far. Of course, Autolite and Motrocraft coppers are the favorite here.

 

Getting no codes with either test AND a flashing CEL is rather difficult to believe. This would lead one to believe that somehow the computer is miraculously being cleared of its memory between driving and shutting it off OR you have wiring to a sensor that is shorting and causing intermittent false info to the ECM. Even so, the ECM should store any Codes significant enough to cause the CEL to illuminate. Heck, it stores lesser Codes all the time.

 

I double check koeo, and cm test with jumperwire (last time i use Lauch diagnostic tester) Now it shows 21 (ect out of range) and 24 (iat out of range) in koeo and 32 (egr) in cm test.

I made test with cold engine (air temperature 50f) , can that explane codes 21 and 24?

If egr is stuck open, can that explain symptons, engine is running too lean?

 

Ford Fuel Injection » 2 Digit Self-test Codes 11-32 and read the possible causes in Ford Fuel Injection » EGR Valve Position sensor (EVP)

 

21 and 24 are probably because of the cold engine, run it at temp and make sure. Double check EGR, that COULD definitely be the cause.. You always want your EGR running right. It's easy to just put a vacuum line on your EGR valve and suck through it to see if it moves properly, if the diaphram has a leak you'll be able to tell by doing that, or if it's stuck either open or closed.

However, I can force my EGR open and my engine runs decently, just some stumbling, no hard miss or anything.

I do want to say, when I have a bad crossfire I will get a flashing check-engine and it holds and shows absolutely 0 codes in my 1990 with a 351w. .. I get no check engine light OR codes with a misfire at all.

I've messed with a few vehicles and this (and my old Bronco with the 302) are the only ones I have ever had a crossfire with. I thought it was old bad wires, but with new Ford Racing wires I still have to be extremely careful with plug routing.. Nevermind having the wires wrapped, it's not required to cause it, on my particular engine (the 351w, your firing order is different) my 7 and 8, 1 and 3 cannot touch at all.

Check for carbon tracing on your wires, make sure they aren't grounding out on your block, shorted or crossfiring with another wire. I'm serious about how critical it is with these two engines.
I hate throwing all my eggs into one basket but it's worth a serious consideration, I dealt with this in two different trucks, a 1980 Bronco with a 302 and a 1990 Bronco with a 351w..
I had this exact problem once when my 7 and 8s were touching is the only reason I'm so stuck on this, it would sorta drive fine, but when I put my foot into the throttle I would get sorta reverse torque like the fan was hitting something, the 'check engine' light would flight when it happened. Immediately I checked codes and it showed all 1s.

 

when was the last time you gave the motor a tune up and checked the timing. are the plug wires originals or have they been replaced?

the knock you hear going up hill is probably detonation.

you must have the motor to temp before pulling codes.

 

I was thinking this as well. If your CEL is coming on and you have no codes then you have bigger problems. Are you disconnecting the battery every time you drive it because of a drain?

 

Yes it is detonation when accelerating. Crossfire is bossible, new wires and plugs are waiting to be installed. I think there is original wires now.

 

also check the timing with a light.
get the motor to proper temp and with the spout connector removed get the timing to 10*btdc and synch down the dizzy, turn off engine and reinsert the spout plug. start the motor up and go for a drive.

do this after you have installed the new plugs (motorcraft or autolite copper only) cap/rotor and wires. I recommend you swap the plug wires one at a time so you are sure to get them in the correct spot. much easier

 

Detonation proplem is solved! And i feel little stupid Sparkplug wire no.3 was not fully down in sparkplug. Detonation stopped, but mil is still blinkin when i accelerate on higway. I have not had time to check egr or change new wires and plugs yet.
I will do fully tune up and service to car when i have time for it. This Bronco is quite new to me, but will stay in the family long time!

 

good job, after the tune up be sure to pull battery cable and wait 15mins then reconnect and drive truck for a good 30mins thru various driving conditions. hwy, city etc. help computer relearn.