Jackthewac

so i have a 1998 sr5 4runner with the 5vz. 255k auto 4wd. i have a missfire code for 5 and 2. #5 has no injector pulse i checked at the ecm and found that there is no signal there. repalced the ecm with a supposed good one and the same thing no injector pulse at #5. ( haven't checked #2 as it is hard to get to the injector just to test). i ran a new wire and the n tested the circuit by moving the pin from #5 to #1 and found that the noid light lit up. so the wire and terminals should be good. am i overlooking something? or do i have an other bad ecu?

75w90mantraN

Doubt the ecm...truck would have a lot of other weird stuff going on.

Noid light coming on yet no pulse? Think the one you tested is good.

Usually, one starts with plugs wires, coils with these misfires before moving on

Jackthewac

ecm can fail on a single cicuit. but if its not the ecm why is it not sending injector pulse? what should i be checking next?

Jackthewac

i replaced the plugs wires and moved coils already. also new fuel pump, fuel filter, maf, injectors, cam position sensor. sorry i have been tracking the problem for a while and made a post on another forum for a few weeks with little help. and noid light didnt light up on ciruit 5 until i moved the terminal at the ecm with a known good one ( injector 1)

75w90mantraN

Then its probably electrical in nature.
I'd check things like continuity of the wiring involved. Seems like the components themselves are not the issue.

Hopefully someone can help you on the ecm question. Sounds like it was a salvage part, the replacement. What yr from? What's the history on the previous ecm?

No other codes besides P0302/P0305?

Jackthewac

only 2 codes I have and I have power at the injector just no signal ground from ecm. I ran a new wire still no signal. I'm trying to find if the ecm needs any input from anywhere to determin when to inject on the cylinder. maybe cam position? crank position? idk the ecm I got was used but I cant afford a new one and a reman takes a month to get. I'm pulling the timing cover tonight to see if any teeth are mission on the cam gear that the cam sensor reads from.

75w90mantraN

Yeah, mechanical misfires are definitely another thing to look at. Though I'd think you have a random/multiple misfire code or none at all. Are you getting any knocking noises?

You mentioned switching coils....from a good cylinder and no change?

Jackthewac

i replaced the ecm and got injector pulse at #5 now but found that the injector has only 8 ohms others all had between 13.5 and 14.8. i replaced all of the injectors 3-4 months ago. i tossed in an old injector that i knew was working ok on removal. now its running good but i have a flashing check light at 60+ mph crusing the code is the same missfire #5 and #2. the missfire is not felt at the at all. i pulled the plugs to see if they were fouled out they look ok and i have spark. i checked over what i had removed for any vacuum leaks or anything else and found nothing. this truck is killing me.

75w90mantraN

If you had to go back and replace an injector that was relatively new, I'd backtrack and check all the other parts that were replaced. Anything refurbished or not good quality is suspect.

What if you put back the original ecm...?

Jackthewac

old ecm still has no pulse I'm suspecting that the injectors low resistance may have alawed to much amperage and caused the circuit to go bad in the ecm. but that's just a guess. really weird stuff man. every part I replaced was new ngk or Toyota parts except the injectors were refurbished ( couldn't afford 6 new ones from Toyota at 160$ each!) I'm wondering if I have another issue like internal because I felt the miss today coming to work I got on it alittle to pass a slow driver and at about 4k it felt like the truck back fired some. maybe a burnt valve? idk seems like it would happen all the time for a valve but I'm guessing here. I have switched wires around plugs around and coils the code keeps coming on #5 and 2. I checked spark with a spark tester and the spark is strong. any ideas what this could be?

75w90mantraN

https://www.yotatech.com/forums/f116...-pulse-237170/
This thread, although for different gen, sounded similar to what I think you may have -- an electrical issue. Summary of that story was a new engine harness solved his problems with no injector pulse.

In the meantime, maybe try to find a wiring schematic to test for continuity of the affected injectors for #2 and #5.

There have been others' cases where it turned out to be a problem with the reman injectors, but no injector pulse is definitely electrical.

Resistance is one important marker of the wiring flow of current, continuity would give you an idea if the wiring is intact. No continuity would mean there's a break somewhere. Could also be corroded, dirty, or loose ground connections.

As long as you drive below the threshold of flashing CEL, should be somewhat safe. Flashing means expensive parts like cat converters are taking a hit from the misfiring, since all the combustion gases are out of whack.

Really hope you get it running good like it should.

Jackthewac

thanks man. this truck is confusing the ˟˟˟˟ out of me I ohmed the wire and had .3 ohms to the ecm so that should be good. I took a few grounds off and cleaned the hell out of them and put dielectric grease on them. I'm pretty good with fixing vehicles but this is a real head scratcher. I hope not a harness that would be expensive or get a used one that would make me nevous. I just saw a video were a guys crank gear was worn out and it kept turnin on the crank making the truck go out of timing alittle. my t belt looks a little old so I might change that anyway and check that gear. I feel like that would throw some kind of corolation code but you never know I guess.

Jackthewac

It was the crank sproket. The last guy to be in there left the bolt loose. Thanks guys. It runs awesome now.

75w90mantraN

Mechanical misfire after all! Great work! And Nice shots! In time for the New Year