code diagnosis

[Wicked_Sludge]

keep us posted.

 

[86jalopy]

got the miss squared away,the injector had a piece of crud in the little filter up top.


my buddy ran a pretest to see where the truck was at and it is running way rich.i still have codes:

84
89
29
41
33
34

i manually tested the egr solenoid and it has 12 volts constant,if i ground it the egr will stall the engine.the o2 sensor is new.if someone has an ecm pinout i can test the o2 circuit back to the ecm.i also bought a new vss and cant find one on the truck or even a plug or harness for one,any ideas?

 

[Wicked_Sludge]

by running rich you mean your hydrocarbon count was high, right? that could be from a failed cat converter. otherwise, it'd be odd that his tools show it as rich and the PCM thinks its lean (code 41)...unless the signal isnt making it to the PCM. you can back-probe the O2 and see if its switching like it should be. if it is then you know theres a wiring problem. if it isnt, then it is really running lean.

the EVP (code 84) might be a grounding issue at the PCM. since you have 12v at the solenoid, i assume the PCM grounds it to open the valve. if the ground the PCM uses for this isnt solid, it will cause an open circuit. im sure the codes 33 and 34 will go away once you get the EVP to open when commanded to by the PCM.

the VSS should be located on the rear differential. on the top, slightly towards the front and drivers side of the vehicle. if its missing, someone swapped a much older axle into the truck and the harness is probably tucked up out of the way somewhere.

i dont know what to say about the code 89 other than you probably wont be able to fix it without swapping computers or swapping in an automatic. MAKG, if your still watching, do you happen to know what kind of feedback the PCM looks for here? is there any way he can trick it to get the CEL off?

you might try making a seperate post and see what others that have done 5 speed swaps have done to clear this code.

 

[86jalopy]

i swapped the computer to a 5 speed and have yet to drive it other than around the block.i have a new vss cause there isn't one on the truck at all.i also cant find the harness for it anywhere,i may have to run new wires to the pcm.on other 86's i've seen the vss is on the speedo cable on the back of the trans.i will check the rear axle though.

by rich i mean the hydrocarbons are 3 times what is allowed to pass.

the cat maybe crapped out from running rich for so long,but i cant buy another one in california yet because of some new law.

i think most of the problems are in the wiring.

 

[86jalopy]

no sensor anywhere on the rear axle housing.

 

[Wicked_Sludge]

so there is no speed sensor in the rear diff or the transmission/transfer case tailshiaft? thats very odd...did that 5 speed come out of a 2.8 truck by any chance? since the 2.8 was carbed, it may not have had a provision for a VSS in its transmission. but still, the wiring should be there somewhere...

very odd indeed....

 

[86jalopy]

not in either place,however the trans may have been changed,it's a 200 dollar former farm truck.

i could hook the vss to the speedo cable and put it in the trans easy enough i just got no wiring to plug into it,it may have been cut out at some point.

i've heard back and forth about some trucks without "rabs" (whatever that is) not having a vss.it has no cruise either.i will get a chance later to drive the truck with the new ecm and see if the codes change.thanks for the help and any other advice is welcomed.

 

[Wicked_Sludge]

RABS (rear-wheel antilock brakes) were used in mid '80's to late '90's ford trucks. even if you dont have RABS, all ford fuel injection computers require a VSS input, hense there should at least be a VSS in the tailshaft.

 

[JTH1972]

now you got me curious to see if there's one on mine!

 

[86jalopy]

if you find one please let me know what color the wires are that go to it are.

 

[86jalopy]

as far as i can from hunting through wiring diagrams is that my 86 doesnt use a vss.

i ordered a new ecm for an 86-5speed-ca emissions ecm today,should have it wednesday.

 

[86jalopy]

put in the new ecm and it purrs like a kitten,tomorrow i will drive it and check for codes.

 

[86jalopy]

well the new codes are as follows:

koeo
11

cm
34

41
77
25


i will double check fuel pressure and put in the new o2 just cause i have it.the truck has only been driven about a half mile so i am not sure about the code 34.the truck was running in the drive for about 20 minutes.

 

[Wicked_Sludge]

code 11 is the "A-OK" code...so we must be getting somewhere.

still getting that pesky EGR code 34 though...did you ever check the PCM grounds?

41 is a lean code. try the new O2 since youve got it.

77 isnt important.

25 is a knock sensor code...thats interesting because i didnt know 2.9's had knock sensors

 

[86jalopy]

the grounds are there but i will clean the paint so they are bare metal tomorrow.

since the ecm is one could i ordered from autozone could it be looking for a knock sensor thats not there?

could the code 34 be from not having enough drive time on it?