chrishf12

My truck has been throwing CEL code 14 for about 2 years now. At first It would only do it every couple months and recently it has gotten so bad it is agrevating and my dad is pushing hard to sell it but I wont let him because I love my truck!

The truck starts up and runs but when you go to stop and push the clutch in the CEL comes on and the truck cuts off. If you keep the truck tacked up a little it does not turn off...but after a few seconds the CEL will go off and there are usually no problems until you try to stop again. Every once in awhile the truck will sputter and sometimes turn off when slowing to turn onto a side road but will start up and keep on going by letting out on the clutch. To me it only seems to happen at low RPMs.

The only code the truck gives me is 14 which says that the ECM is not getting a signal from the ignitor for 4 or 6 (cant remember exactly which one) ignitions.

I have replaced the entire ignition circuit. I have replaced the plugs and wires, electronic pickup in the distributor, distributor cap and rotor button, ignitor coil & assembly, and the ECM. I even replaced the EGR valve about 2 and a half years ago. I have cleaned all the grounds I could find and made sure they are tight.

One of the best toyota mechanics in my town says he is not exactly sure where it could be coming from but we did pull and plug the vacuum line off the top of the egr valve. The truck ran good for 2 days and didnt cut off then it went back to doing the same thing as before with the vacuum line still plugged.

I have taken the truck to the dealership they worked on it, charged $200, and the truck still does the same thing as when we took it. They said they were pulling the same code out of the ecm but had no idea what the problem could be without just pulling and replacing parts

This is getting to be a big prob if anyone could give me an idea of where to go from here or what to look for I would greatly appreciate it... I DONT want to have to sell my truck.

thook

Here's a test someone posted a long time ago.

https://www.yotatech.com/forums/f2/n...89-95-a-10543/

I realize you've had extensive work done already, but something you didn't mention caught my attention. It would be worth checking.

The last check will be to make
sure the Black wire does not show full continuity to ground. This wire goes
to the Tachometer, and if grounded somewhere in the harness, will keep the
Igniter from working.

As well, this excerpt from the linked post caught my attention....

The Fix: Replace the defective parts determined by the above testing. Don't
forget, if you do end up replacing the Igniter, double check Coil
resistance to avoid damaging a new Igniter.

As a last resort, I'd have the wiring harness to the ECU double checked. Plus, have your mechanic...that "best" Toyota one....look this info over in case something was missed.

chrishf12

Thanks I havent found that thread yet..I replaced the coil first about 4 months before the ignitor assym and ECU so maybe the old assembly damaged the new coil.

abecedarian

The code basically means no spark for 2-3 crank rotations.

Definitely check the tach signal wire for shorting.

When you said you replaced the ignitor coil and assembly, you mean the ignitor module and coil, correct? Did you get the correct ignitor for your truck? Did you buy it new or used? There are 3 ignitors available for my 88 so possibly yours has different ignitors available as well. One quick way to check is to compare the colors of the plugs- if the ignitor plugs' colors are different than the harness' colors, it's likely not the right one. Also, there is a part number on the ignitors so make sure they are the same part numbers because as I said there could be different ignitors available.

Now I can't think of an immediate reason why depressing the clutch pedal would cause the CEL to come on unless there is an intermittent short in the wiring behind the dash and the pedal may be contacting a wire, or there is a short in the clutch safety switch wiring. And since you also say it occurs sporadically when slowing to turn, I think it could be a wiring issue. So break out the DVM and start checking wires. Double check all the terminals are fully inserted in all the connectors.

You may also try starting the engine and let it idle, then gently shake and tug on the wiring between the distributor and ignitor to see if you can reproduce the symptom.

Going out on a limb here- the only other thing I can think of is that you have a fuel mixture going too lean or a coil with incorrect resistance causing a moderately weak spark. Under deceleration, the ECM leans the mixture out. It takes more spark energy to ignite a lean mix. If the spark plug can't fire properly, the ECM can detect it. Given that, fuel filter, fuel pressure regulator or fuel pump, throttle position sensor, air flow meter and coolant temp sensor all can affect the mixture. Since it's happening under deceleration with the throttle released that could imply fuel pressure regulator, TPS or AFM are slighly out

thook

Dang Kirk......good posting.

Yeah...a wiring issue sounds like it to me.

chrishf12

Yes i replaced the module and the coil with Denso parts from carquest part #s and wires matched I still have the original (Electronic Pickup, ECU, Ignitor module). I have replaced the fuel filter and checked the AFM it is not sticking. I cannot reproduce the problem by tugging on any of the wires including main wiring harness. I have tried many, many times. I have plugged and unplugged all of the wiring harness connecters to hopefully "clean" the connections.

I have thought about the leaning out of the mixture but dont know the best place to start looking for that. After it ran completely fine for 2 days I started looking to the vacuum and emission system thinking the air/fuel mixture was getting messed up from there. Should I start looking into sensors or vacuum issues in emmision system first? The FSM leans more towards the vacuum issues with the symptoms I have discribed.

abecedarian

it's entirely possible it is a vacuum issue, for no other reason than that the intake manifold vacuum is highest at high-rpm/closed-throttle conditions and a vacuum leak then could lean the mixture enough to misfire.
I would be looking at the throttle body area, pcv valve, grommet and piping, intake manifold gaskets, brake booster piping- anywhere a major vacuum leak could occur.

chrishf12

I want to think this is electrical simply because it doesnt happen consistantly (at every stop). But because of the way the truck acted after plugging the EGR line it made me think the problem was there. Is there anyway I can prove or disprove it being in the vacuum?

About Feburary this year I blew a head gasket and replaced the intake manifold and exhaust manifold gaskets along with any other gaskets that I had to clean off getting to the head gasket..I made sure none of the gaskets were messed up on install and all vacuum lines and wires were marked. All hoses looked fine to the eye. I still had the same problem before and after the repairs.

abecedarian

I'm starting to think it would be a good idea to take it to a shop that has a dyno and strap it down and make it do it. The shop should be able to have a diagnostic computer and tailpipe sniffer hooked up so they can monitor the engine conditions when it happens.


Out of curiousity, can you get it to throw the CEL if you're in the driveway and just rev the engine up to 3000 or so and let off the pedal?

chrishf12

Every now and then it will especially if I drive it a while before I try. I can come in the driveway and it will cut off, if i crank it back up it will run for a second or two then cut off usually it will start up and turn off a number of times in a row then sometimes after turning off the first time it will start up and run for 10 min straight and not even sputter. but if you jus lay your foot on the pedal enough to raise the RPMs by a couple hundred it does fine until you let off.

abecedarian

I'm going to rattle of a few other things you can do that may help the situation, but may not. at worse, you'll know they aren't the cause of the problem. Feel free to comment.
adjust the valves.
replace the PCV valve and grommet
check the fresh air intake to the valve cover from the throttle body.
check the TPS sensor operation and adjustment:
http://4crawler.com/4x4/CheapTricks/TPS/index.shtml
check the air-flow meter:
http://4crawler.com/4x4/CheapTricks/AFM/index.shtml
replace the fuel filter.


another couple of curious questions:
any chance the coil is connected backwards?
what type of plugs and what's the gap set at?

chrishf12

Fuel Filter has been replaced, I have adjusted the valves, PCV doesnt rattle and grommet appears fine (I may replace anyways), clamps on fresh air hose from tb to valve cover are tight and hose looks fine (no cracks/heat marks)

I have been mechanicing on diesels for my uncle for 4 years now and havent had a problem that stumps anyone this bad...Im just lost LOL

chrishf12

Thanks for the info yall have given me some things to check and recheck hopefully it will help me diagnose this...

abecedarian

hey, I hear ya. I'm a certified (or at least was 18 years ago) cat, cummins and detroit mechanic.

but you said the pcv doesn't rattle...? it's a jiggle valve and the new one I put on my 91 22re rattled out of the package.

chrishf12

It checked good last time I checked it couldn't remember exactly which way rattle or no rattle but I am gonna check it again.

thook

Good God....vacuum/leaning out kind of makes sense given that the problem is produced when there's a vacuum load from brakes and turning. I would have never thunk it.

Good luck.

chrishf12

Ok I just talked to my dad tonight...he has been driving the truck for the last few days because i am at school. He said he filled it up with premium gas and fuel injector cleaner because of similar problems on a ford expidition we once had. And so far It hasnt messed up on him in the last 3 days. How can this keep the engine from misfiring? I was running fuel injector cleaner in it before the head gasket blew during repairs the head was extremely clean for having 160,000miles on it.

So how can just running premium gas have this effect? I know it allows more compression when running..but I dont understand how It can correct a misfire?

abecedarian

hmmm....