Occasional hickup DM run ADDED see post 37 FIXED post 40

Don W.

Don W.

Stab it and steer it
OK, briefly the Sy died last week. Replaced the coil fired back up. Replaced the module for good measure. Truck starts a bit quicker, especially when warm. Runs nice, EXCEPT...

Slight lope at idle. Always been there, just mention here in case.

So, I head off down the street and I have a random miss. Almost a shut down only it happens for such a short period of time it's hard to call it that. Things that happen when this occurs are:

Tach dances 4-500 RPM up, down, or both.

Caught one very quick flash of the CEL, no code on DM.

WB goes lean. I assume here the inj's have quit for that 0.1 of second that it happens.

Trans drops out of lockup.

Caught it in one DM log. On just one record ECM went from closed loop to open loop and back.

I plan to start by eliminating some obvious items. I'll bypass the bat kill switch. I'll replace fuses even though they test good, ya never know. I've already bypassed the MSD 6al, no difference.

Doesn't seem to happen at full throttle but haven't done a 0-100 pass either.

My hunch though is somehow the ECM is going "off line" so obviously will check everything there as well.

Someone said I should check the pet rat on the wheel but last time I looked he was still going.

I'm NOT a fan of intermittent electrical gremlins.

Thanks all.
 
Last edited:
WyoSyclone

WyoSyclone

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

I wonder if a bad temp sensor/connection could cause some of this... the idle variance and the closed/open loop could be effected by a problem on this circuit. The temp sensor for the ECM is in kind of a bad spot.
.... just something to think about.. :dunno:
 
SY-1193

SY-1193

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

Check spark plug wires. Go over them closely for any wear marks splits or rub thru. One trick you can do is turn off the lights in the garage at night and peak under the hood while someone revs it to see if there is any arcing going on in the ignition wiring. (could be the cause of the coil failure? WB goes lean because there is an arc in the exhaust now not to mention the short to ground which would explain the ECM hiccup also?). Look at the distributor cap too.

HTH:tup:
 
Don W.

Don W.

Stab it and steer it
Re: Occasional hickup miss

Re: Occasional hickup miss

Don't know about the temp sensor causing this but I know where it is.

I would think the wires would fail under full throttle but will check. Cap is new.

I intend to peruse the entire ECM wiring and the diagram in the manual looking for problems.

I'll see if I can catch some more of this on DM. That should help.
 
wildphil

wildphil

I Love My Ty's
Re: Occasional hickup miss

Re: Occasional hickup miss

If it didn't have this issue before you replaced the coil and module. I would check and make sure that the problem is not the parts that I replaced. Or something I came into contact with while doing that work. Like the red and white wires from the coil maybe. I had one of those wires go open under the insulation before. I would be driving down the road and my truck would cut off and back on. Just a suggestion.
 
B

bonesdmz

In Mother Russia Typhoon drives You!
Re: Occasional hickup miss

Re: Occasional hickup miss

Is your ICM good? Any chance you occasionally rotated the distrib while changing module?
 
Don W.

Don W.

Stab it and steer it
Re: Occasional hickup miss

Re: Occasional hickup miss

Still checking everything. Dist was actually removed to check the gear. I thought of it being either of the new parts but if so why the electrical issues? Module? Yes. Coil? I doubt it.

Anyway, I'm not against changing the module back.

Further checking today is still keeping me focused on some sort of electrical gremlin. I'm only getting 13.6 volts inside the cab. Coincidental alt failure? Will check further.

I keep thinking something has gone haywire with the firewall connection to the fuse block. I can check that has anyone heard of this before?

How much voltage does the ECM need to operate correctly?

Will pull alt and have it checked. I've seen low voltage like this before and it was the just the brushes in the alt.

One item I forgot to mention is I have an inverter in the cab to run the laptop. When it's input voltage goes low it beeps. It will occasionally beep when this issue happens indicating a momentary loss of juice in the system. If I can figure this out I think I will have found the problem.

Please keep all ideas coming. I appreciate them all.
 
turbodig

turbodig

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

Bad ground. Check/clean the cyl head grounds and the one behind the alt.
 
DaveP

DaveP

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

Random thoughts based on observations listed.
All of the electrical devices you list in your opening post are on the same red wire / fuse link from the alternator.
They are also all switched ignition circuits.
Your inverter "low voltage" beep is significant. The interruptions in the above devices seem like a power interruption, not particularly a low voltage issue.
The bulkhead connector is very reliable. However I have found resistive connections in the red wire terminals on a few vehicles. Be warned: This is a very fussy connector to deal with as far as cleaning and inspecting. The black tar crap will really frustrate you. And the female portion is on the car-side, and requires working with from under the dash. Very challenging, as there's no room to work. I would suggest performing voltage-drop tests to check, rather than a visual inspection. At least to begin.
I know you have a battery relocate. So check ground paths using voltage drop methods.
Alternator must have good ground path to the engine. Engine must have good ground path to body. Black/wht ground on rear of head is for ECM. Big black at front of engine is for Inst Panel / Interior. And is through bulkhead connector as well.
Check alternator voltage under load. Turn on as much stuff as you have. Lights, blower, put a load on your inverter. Check alt output voltage. These CS130 alternators are POS. The stators burn out, and don't produce any voltage under a significant load.

There's some ideas. I would begin by getting out the VOM and checking as many current paths as you can devise to check with voltage-drop methods. If you don't understand what I mean, please ask, and I'll explain. You might also try wiggling and tugging on wires and connectors with it running. You might get lucky and make it stall. Then you'd know you're close to the problem. Good Luck.
DaveP
 
Don W.

Don W.

Stab it and steer it
Re: Occasional hickup miss

Re: Occasional hickup miss

Thanks Dave. First, I understand what you're talking about.

However I have two questions:

How much is "to much" voltage drop? Say across the bulkhead connector.

And, is the fuseable link at the alt repairable or does the wire get replaced? I ask this one because I was wiggling wires and things -seemed- to change when I wiggled the links. I cut the shrink wrap off the connector and that looks good.

A couple of years ago I actually had the engine side of the bulkhead connector off so I know what you mean there. It's not difficult once you remove the wheel well. I fully intend to check that again.

Been very busy at work so should be able really tackle this problem this weekend.

When I find it I'll post it...
 
DaveP

DaveP

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

Thanks Dave. First, I understand what you're talking about.

Cool. Think of things to check. Using the 1V scale, put your meter on two points, and imagine the "path" between those two points. (I don't pay attention to polarity). Grounds should be 1/10 Volt or less. maybe 3/10V from battery to alternator case with engine running.

How much is "to much" voltage drop? Say across the bulkhead connector.

Depends on the current. Check it with minimal load, and again with as much load as you can put on it. I'd be OK with 1-2/10th no load and perhaps 3/10 with some load.

There are two red wires. Both go through the C100 bulkhead connector. One goes to the ignition switch, and becomes all sub-circuits that are switched by the ignition switch. The other is "Battery hot" corcuits. Like the light switch, and the HRN/DME circuit. So keep this in mind while assessing voltage drops on the two circuits. Also check the ground from the lighter plug to the alternator for drop. This ground wire goes through C100 too.

And, is the fusible link at the alt repairable or does the wire get replaced? I ask this one because I was wiggling wires and things -seemed- to change when I wiggled the links. I cut the shrink wrap off the connector and that looks good.

Fuse link is replaceable. Cut the big yellow/clear insulator off the splice, and cut the splice. The link is a 1MMsq X 4" . Check it by tugging length-wise on it too. Particularity at the terminals. It may be partially melted internally. I use heat-shrink butt connector splices to renew the links.

A couple of years ago I actually had the engine side of the bulkhead connector off so I know what you mean there. It's not difficult once you remove the wheel well. I fully intend to check that again.


The female connectors on the car-side of C100 are the ones that become resistive. They open up, and don't make good contact. You might be able to massage the terminals tighter by picking at them with small tools from the engine-side of the bulkhead. I'm not sure. Clean off the male terminals and take a look. If they look discolored, they've been hot, so look more closely.

When I find it I'll post it...
Good Luck.
 
T

turboj91

New member
Re: Occasional hickup miss

Re: Occasional hickup miss

The female connectors are the ones that become resistive.

They open up, and don't make good contact.

You might be able to massage the terminals tighter by picking at them with small tools

Clean off the male terminals and take a look. If they look discolored, they've been hot.

I can say I have had experience with all of the above.
Now back to the situation at hand. Sorry. Couldn't resist.
 
JSM

JSM

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

turboj91 said:
The female connectors are the ones that become resistive.

They open up, and don't make good contact.

You might be able to massage the terminals tighter by picking at them with small tools

Clean off the male terminals and take a look. If they look discolored, they've been hot.

I can say I have had experience with all of the above.
Now back to the situation at hand. Sorry. Couldn't resist.
Click to expand...

Thats funny, makes me wonder if Dave is trying to help Don with his truck, family life or both.

Hmmm
 
DaveP

DaveP

Active member
Re: Occasional hickup miss

Re: Occasional hickup miss

I saw Jim's post last night. Now Jeff gets in too. It's nice to have friends, because you can count on them to keep it yucked-up around here. It is kind of funny when read out of context. Having never been married, I have no idea what you two are talking about. I was writing about electrical systems.

OK, back to Don's electrical issues.
 
Don W.

Don W.

Stab it and steer it
Re: Occasional hickup miss

Re: Occasional hickup miss

I enjoy the humor.

First I have to apologize, the truck has an alarm and I didn't mention it. I didn't because I don't use the thing. It only comes into play when I disconnect/reconnect the bat. That sets off the alarm and I disable it and forget it 'till next time.

That being said I was checking wires. The power connectors (2) to the alarm seemed a bit loose so I redid those connections. No difference. That's not to say that the alarm wiring under the dash doesn't have something loose. I will check that and maybe even remove it. Until I get to the module I won't know for sure but I know it's a Clifford and I think it's an ACE 100. One of their first, if not the first.

So anyway I'm sitting at the shop door just letting it idle and it skips. I fire up the laptop and start logging and just wait. A minute or two go buy, idle is smooth, and then it dies completely. No skip, just quits. I try 3 restarts and it won't start. I shut down the laptop, try one more restart and it starts and runs normally. Frustrated, I park it and go home.

It occurs to me I may have more than one problem. Oh joy.

I'm having trouble getting the DM file off the laptop but I don't see what may have caused it to quit. I'm back to changing the module back to one of my originals. Only takes a few minutes. I will try that next. Along with the alarm wiring.

Meantime when I get DM file I'll post it.
 
IpHoOnDyou

IpHoOnDyou

New member
Re: Occasional hickup miss

Re: Occasional hickup miss

Sounds like you may have a weak ignition module to me! If they are weak and get to hot they will shut down
 
wildphil

wildphil

I Love My Ty's
Re: Occasional hickup miss

Re: Occasional hickup miss

Did you try to wiggle the connectors/wires that plug into the distributer and go to the coil to see if it will kill the engine?
 
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