I daily this truck so I'm in a bind. It's a 92 3.0 5spd 4x4.
I came out from work to start it to go home, nothing, no buzzer, dome lamp, bat gauge barely moves. I left the headlights on all day. I tried to clutch start it, it wouldn't fire. I got jumped and it started right up but was running really bad. I tried driving around thinking the low voltage in the battery was causing the rough running, inability to idle. I gave up and got a friend to run me to get a battery, it was still running rough, but i decided to try and make it home 30 miles. It is fine as long as I'm just barely on throttle, any more and it bogs. I live in western NC so going uphill was a struggle, had to drop it into 2nd on the highway to keep from getting rear-ended. It was running great on the way to work and it's hurting my brain, all i can think is the low voltage did something to a sensor somewhere. Any help or places to check are appreciated.
Edited for spelling

 

The most recent thing I've done before this is installing a new radiator, of course flushing and bleeding the system, that was 2 weeks ago. I also pulled the a/c system while i was putting in the radiator as the ac lines were toast. The only thing left in there is the compressor and evaporator. I did the egr delete (yotashop) a month before that and it's been running great. I made a new ground from the head to the battery neg. I've unplugged the cold start injector, can't seem to get it to go into diagnostic mode jumping te1 and e1, check engine light stays on solid, and off when it's running. I pulled the dist cap off, it looks like the rotor button has been making some contact in there, but, like i said, it was running great before the battery flatlined. I'll order a new one to be sure. But i don't think that's it. It makes me think something in the ecu was damaged, but it wasn't jumped backwards or anything.

 

This is a stumper. As a general rule, LOW voltage/current doesn't cause problems, other than for chips.
Did you check the battery terminals while you had them off for corrosion, either on the terminals themselves, or where the cables attach? Normal lead-acid batteries outgas acid mist, ESPECIALLY when charging. It gets down inside the insulation of the battery cables, and causes all kinds of hidden problems. Flex the cables, especially the ones going to the positive terminal, and see if anything changes.

You might want to make the battery negative cables go to the body metal. Either make a separate cable from the one going to the head going directly to the body metal, and route the head's cable to the body metal, or leave the head's cable direct, but add a negative to the body metal from the battery. The body metal is where a lot of circuits get their ground, so it's important to have a good, strong, connection from it to the battery.

Good luck!
Pat☺

 

I added a 4ga ground to the chassis when i first bought this truck 10 years ago, I'll double check it, i cleaned all the paint of and made sure it was good then, but who knows after that time?.. i did notice it looks like the rotor has been making contact with the cap on the distributor. I put a new cap and rotor today which didn't help, and cleaned the throttle body/ checked tps. I'm leaning in the direction of a mechanical issue in the distributor as it's original. Had a friend from work help out today, but only both agree it could be the distributer. We checked for vac leaks and couldn't find anything. It just won't hold idle, sometimes when trying to keep the idle up i can hear pops back through the intake.

 

I hate throwing parts at a problem, but I'm fairly sure it's the distributer. Through the research I've done in thinking either that or ignitor or ecm. The engine has always had a lumpy idle, like it has big cams. Also it acts exactly how it is now, missing, not wanting to idle, no power when i park for 20-30 mins. And try to restart it warm. That'll usually clear out with 3 or 4 minutes of driving i always associated with heat soak. I just changed the radiator based on that and hearing the clutch fan pushing while idling or at low speed. ( i live on a long, windy mountain dirt road)

 

I got the distributor in today, it idles now. Making progress. Timing is off the chart, like 25 degrees advanced. Adjusted the tps to bring it down some (15 degrees maybe) but still have the cammed out v8 idle. Found vac leak under plenum while it was idling today. Ordered igniter, plenum gasket and new pcv and grommet. I did check that i didn't get the distributer a tooth off. I tried it one tooth both ways and it would barely start and no idle. I think the leak under the manifold must be pretty good it revs up when spraying starting fluid at the throttle body (which i thought was the original leak) but spraying under the right side of the plenum it is evident the plenum gasket or something under there is leaking. I replaced that gasket a couple years ago while doing injectors, but, i had it off and on about 4 times as one of the new injectors was doa. I think the ecu had been compensating for the bad distributer and lost that when i drained the battery. But not ready to hit the road at 15 degrees advanced..

 

Did you check the timing with the jumper in the test block before you checked without? Is the idle speed set to 800 RPM-ish?
The book specifies that after stabbing the distributor, and there IS a correct way to do that in the book, to set the idle speed to 800, with the jumper in, and then check that th timing is 5°. Then, after rechecking/resetting the idle speed to 800 again, as required, you pull the jumper, and check the timing at idle again. It should be about 12°.

With the timing set properly, the distributor lock-down bolt should be roughly centered in the slot it rides in. If it's crammed up tight to one end or the other, you need to pull the distributor, and stab it again. If you need the correct procedure, I can copy the right FSM page for you. The timing is adjusted by rotating the distributor, not the TPS.

With the plenum on for "a couple years", you should have replaced the gasket when you pulled it off in any event. They last a long, long time, if undisturbed. If you pull the parts they seal apart, it usually trashes the gasket. Even with it installed a relatively short time. ot as bad as the crush washers, but still...

Hope this is a little help...
Pat☺

 

One issue I'm having is i can't get the ecu to go on diagnostic mode. I put in the jumper and don't get flashes, cel stays solid key on, engine off. My diagnostic port has been missing the cover since i bought the truck. But used to have no trouble seeing codes. The only reason i messed with the tps was to make sure it was reading, then did the "quick" move the tps until idle changes, and back it up a little. The truck is idling 800+- according to the dash. I was just hoping i could get the timing close without jumping e1 and te1. I'll retry installing distributer by the book this weekend. I wouldn't think the plenum gasket would go bad that fast, but i did have it on and off several times while diag'ing injectors. There is definitely a leak under there, I'll just have to try to figure out where it is. Thanks for your insight guys

 

TBH, I wouldn't trust the dash tach. I got a tach/dwell meter for when I owned a Chevy Luv, and had to set, and clean, the points every week. Picked it up at Harbor Freight for about $20.00, back in 85, or there abouts. I use it to set the idle on my trucks to this day. It has a screw on the needle's pivot to zero it before use. Nice and accurate to this day, believe it or not
I picked up a cheap timing light at the same time and place. I still use that, too. Handy for checking for a bad distributor, believe it or not. Showed me 3 caps so far that had a hairline crack in them, fresh out of the box. Couldn't see it until I rubbed a greasy finger across the crack.

Anywho...
You might consider cleaning the test connector, and see if that helps the whole lack of a test mode problem. It doesn't take much crud or corrosion to cause problems with that low a current application. That, and apply a small amount of silicone dielectric grease to the connector's pins to protect them. Great stuff. I use it everywhere. Every electrical connection I touch.

I wish you all the best.
Pat

 

I did the plenum gasket, replaced the pcv, and every hose and deleted all the old vacuum line rats nest down to just the fpr vsv, and there's still a vac leak under the manifold. I've never had the lower manifold off. I did see a couple of the injector cup "rims" are broken, so I'm thinking that's my leak. Although, i did replace all of the cup o-rings when i did injectors a couple of years ago. I didn't have replacements this weekend so i put it back together. I went by the book installing the distributer. It idles and runs decent. But the timing mark when using a timing light is still way off. Almost pointed at 12 - 1 o'clock on the crank pulley. I'm tempted to pull the upper timing cover to check my belt marks. I did the timing belt with the Aisin kit, and went by the fsm. It's just still boggling my mind how it went from running good to cant pull slight grade from a dead battery. Could it be the knock sensor? It used to throw knock sensor code, but it just went away one day and started running better. I don't believe it fixed itself, but something happened there. I've got no CEL while it's running, although it does come on with key in acc. Could my ecu be going bad? Cleaned the diag port and still can't get it in diag mode. Maybe my wiring harness is showing its age?

 

Definitely a valid possibility. Certainly should be repaired.

With all the work you've been doing, it's possible you moved/flexed the pigtail from the knock sensor to the main cable. They are known for failure. Readily available for a reasonable price from the dealerships. Only use OEM! Same for the knock sensors themselves.
Aftermarket sensors don't get along well, or at all, with the ECU. Found that out on my 99. The hard way

Keep us up to date
​​​​​​​Pat☺

 

I pulled the upper cover off today, everything lines up great. Anyone see anything wrong here? This leads me more towards an ecu issue. Can anyone chime in with any ideas? I was really hoping to see a cam gear a tooth off, i could fix that...

 

Thank you for your replies Pat! I was uploading pictures while you posted the last reply, I'm going to order injector cups, and o-ring kit, I'll add knock sensor pigtail and lower manifold gaskets in while I'm at it. Still bugging me i can't get it to go into diag mode. Wish i had a spare ecu to test. (Edit) also, wouldn't i have a CEL again if i was having knock sensor problems?

 

Not necessarily. It can trip a code, store it in memory, and not display it if it doesn't go into diag mode the way it should. It's surprizing how often a code will trip, and never show a CEL, until you get the diag mode engaged.

The pictures sure LOOK right.
When you put the new distributor on, did you check the air gap on the sensor inside? And verify the sensor has the correct ohm value? I'm just trying to think of any possibilities I can.
If you can't get the CEL to flash correctly when Te1 and E1 are jumped, yeah, you might have an ECU problem. If you can't find anything else, you might have to replace it. I would make sure it the last thing you try, given the cost. Make sure the ground near to the ECU is in good shape. No corrosion, broken wires, and so on.

Good fortune to you!
​​​​​​​Pat☺

 

I suppose i could jump e1 and te1 at the ecu, provided i can find a pinout. Then I'll know if it's just that old data port. Thank you for the support, I'm going to try real hard to get it into diag mode before i haul off and buy an ecu. 3.0 5spd 4x4 ecu seems to be the most expensive. I can't see any reason an auto ecu wouldn't work though.

 

Unable to jump e1 and te1 at the ecu, it's possible my tps was out of adjustment, preventing diag mode. I pulled the tb after work yesterday and adjusted idl switch, ran out of time to put it back together, and have daughters softball game tonight, so I'll work on her tomorrow. I was also looking at the position of the rotor on the distributer in relation to contact point on the cap, it looks like the rotor is just about to come out of contact with #1 when the distributer is adjusted in the middle. I set the distributer 1 tooth clockwise where the leading edge of the rotor is on #1. Rotor is about 12 o'clock position. I'll see if that did anything. It is idling and revs normally in the other position, just has no power, so I'm not sure whether this idea has legs.

 

Installed my ebay ecu a few minutes ago. Have a flashing cel again! Timing is still the same, I'm going to install my old tps, as this new one is basically maxed out to one side to set idle switch. (Don't know if it matters) it's driving MUCH better, just down my slow dirt road. I'm not taking it far as i know it's at 20 degrees advanced according to my timing light and i can hear the start of some pinging going up hills. Cel came on while driving and it's code 52 which it used to have. Still need to pull lower manifold off one day. But as for now, I'm going to get the timing set and drive it again.