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Fixed: TBI fails for the second time in the same way
After going through all the testing found it to be a bad injector. Swapped them out and fixed it right up.
So I've had this problem before one injector would not spray until the engine almost dies out and then it sprays to keep it alive. I've already changed out filters and o-rings for my TBI. I've also installed a fuel pressure gauge and new fuel filter around the same time I refreshed the TBI. I got a new IAC and swapped out my o2 sensor because I thought the iac, o2, or EGR/all three gave me the problem but ended up with injectors not spraying. Again. After the car has been off for a bit and gets turned on again it will idle fine but then starts doing it again. Also at WOT injectors spray fine.
Details: started after I installed a AFR meter
Fuel pressure:12-10psi
Plugs and oil changed a month ago
Timing advance at 10-12
Installed a MSD Blaster SS coil two months ago just connected wires the correct terminals
I was running the car fine before it happens took it side ways around the block but then I wired the meter and presto injectors again.
Suggestions? Or should I dump it already and swap out a carb? I have a 5.7 Lo5 waiting for a clean up and heads/intake. My Camaro takes me to work and back and picks up my child, but I can barrow a car. Wouldn't like to but I can.
Edit: Car always cranks over fine. No problems with cranking over and starting
Last edited by RevenateRS454; 12-22-2016 at 05:40 AM.
Reason: Extra info
Okay sweet I have somewhere to start. Do I start with what? Checking wires and testing? I have seen a set of wires that have been destroyed behind driver side cylinder head. Have a orange wire poking out of a loom and a brown wire going off somewhere behind the block.
If it is always the same injector then likely there is a wiring issue. The injector wire terminal at the ECM could have a little corrosion on it. Check the wire/terminals at locations C15, D14, D15, & D16.
Note that most likely only two of those four will have a wire in it.
The other problem area which the wiring harness may or may not have are the injector wire splices. Some harnesses run the special wire used for the injectors all the way to the ECM.
Others splice back to regular wire that is then run to the ECM. Those splices tend to break and become intermittent.
It is easy to tell how the harness was made by observing the injector wires at the ECM. If they are that same slick shiny insulation that is found at the injectors. Then it is run all the way to the ECM (no splices).
If it is always the same injector then likely there is a wiring issue. The injector wire terminal at the ECM could have a little corrosion on it. Check the wire/terminals at locations C15, D14, D15, & D16.
Note that most likely only two of those four will have a wire in it.
The other problem area which the wiring harness may or may not have are the injector wire splices. Some harnesses run the special wire used for the injectors all the way to the ECM.
Others splice back to regular wire that is then run to the ECM. Those splices tend to break and become intermittent.
It is easy to tell how the harness was made by observing the injector wires at the ECM. If they are that same slick shiny insulation that is found at the injectors. Then it is run all the way to the ECM (no splices).
RBob.
Okay I had no idea the injectors ran special wiring in the harness. I do have splices. A while back I swapped out the old connections at the injectors for newer ones. I took off the connections off a GM TBI truck at the junk yard truck was very clean and keep. So naturally though it was a good idea.
Looked at the ECM and all said locations have a wire in them. 3 blues and one green wire. Removed my distributor the ICM looks to be connected nothing was lose I did have corrosion on the bolts holding it down and the pick up coil had surface rust. Still nothing from passenger side injector.
I've messed around with it all day. Problem is electrical. Like mentioned before. I swapped out the connections and injector two started spraying and injector one wasn't home. I checked both fuses and both checked out.
My next course of action is what? I don't know who's next on the check list? Track the wires back?
I also tired putting bare wires on each terminal on injector two and nada.
Koeo iirc the injectors have power on the white wire.
Bolth injectors have a driver light blue injector 1 ground splits at a splice and goes to
D15 & d16 of the ecm. Injector 2 is also spliced c15 & d14.
You can swap the plugs at the injectors to see if the number 1 starts to pulse. If it doesn't sounds like it's shorted. Iirc Tbi injectors are low resistance I think they are close to 2.5 ohms.
I've messed around with it all day. Problem is electrical. Like mentioned before. I swapped out the connections and injector two started spraying and injector one wasn't home. I checked both fuses and both checked out.
My next course of action is what? I don't know who's next on the check list? Track the wires back?
I also tired putting bare wires on each terminal on injector two and nada.
Btw there is only one injector fuse, what do you mean bye one want home ?
Something was missing wiring wise ?
Did you apply 12v to that injector
Just a FYI the pu coil is under a cover in the distributor . Cranking with a vom in ac volts the pu coil voltage readings should fluctuate between .3 Volts and 1.8 Volts A/C.
Originally Posted by RevenateRS454
I've messed around with it all day. Problem is electrical. Like mentioned before. I swapped out the connections and injector two started spraying and injector one wasn't home. I checked both fuses and both checked out.
My next course of action is what? I don't know who's next on the check list? Track the wires back?
I also tired putting bare wires on each terminal on injector two and nada.
Last edited by Tuned Performance; 12-16-2016 at 09:41 PM.
Reason: More info
Btw there is only one injector fuse, what do you mean bye one want home ?
Something was missing wiring wise ?
Did you apply 12v to that injector
Just a FYI the pu coil is under a cover in the distributor . Cranking with a vom in ac volts the pu coil voltage readings should fluctuate between .3 Volts and 1.8 Volts A/C.
I swapped the pig tails. Used injector one pig tail and put it on injector two. When I did that injector two fired up and injector one(with injector two pigtail) did not fire.
I'll get myself a meter tomorrow morning. Hopefully I can get it running tomorrow.
Edit: Sorry in advance for my poor typing skills. And thanks in advance for the knowledge bestowed upon me.
And by fuses I mean at the fuse box. Under driver side dash. I have two red fuses inj1 & inj2. Unless one of those is something else.
Last edited by RevenateRS454; 12-16-2016 at 11:18 PM.
With your vom in D.C. Key on engine off you can test the 4 injector driver points at the ecm. IF you have 12 volts on say d14 but not c15 you will know what wire has lost connection at the splice. If you can locate the splice I think it would be fine to resplice down bye the ecm.
Update: Narrowed down problem to injector twos power wire. Now how to go from here?
How I figured it out
Okay so I narrowed it down to injector two hot wire.
What I did was cut all four wires separated the ground wires(green and blue) and hot wires(red and white). I got injector 2(blue) ground wire and placed it injector 2s ground, I then got injector ones ignition wire(white) and injector two started to fire. I did vise versa and nothing was firing with injector twos ignition(power) wire. I bridged injector ones ignition two injector two and it began to fire when it was cranked over, but once it was started injector two shut off. After accidentally dropped the bridged wire on the TBI it stopped working. Checked the fuses and both injector fuses blew out.
I saw a schematic that just showed 1 ign power to the injectors.
The fused power goes from your fuse box to c207 next to your computer under the dash pass side. Out the body and to each injector. Cavity B and G in connecter 207
I checked on everything found the wires. Everything has power. And still no spray from injector two. However I did get my test light and grounded to my car and poked into the injectors wiring to see if power was going, but I decided to poked into injector twos ground wire. When I did that injector two came on.
So pulled down my ECM poked around ports C15 and D14 and It responded to be poking around C15.
Yes and no. I grounded my test light probed C15 and the both injectors fired at start but injector one was still only on after the initial start. But when I removed the probe it injector two sprayed fuel to keep the engine alive. Same when I gave it throttle and injector two sprayed a bit.
I'm not positive but I think one of the injector drivers is going out in the ecm.
You should be able to get a 1228746 ecm in the wanted classifieds for $50-60 .
You would need to swap in your prom.
I'm not positive but I think one of the injector drivers is going out in the ecm.
You should be able to get a 1228746 ecm in the wanted classifieds for $50-60 .
You would need to swap in your prom.
I think your right. I've come around to that conclusion as well. Since I'm gonna get another ECM any type performance(Not in HP or Tq) gains from a ECM? And is the junkyard a good place to pick a ECM or should not pick from their?
Okay I thought I'd have the hardest time looking for that ECM since 89-92 F/B body only. But their is a couple B body Devilles and LeSabres. I'm hoping for a complete easy swap plug and play.... But I'm probably not gonna happen.
Remove the access cover and remove your prom. Install it in any 1228746 ecm.
http://m.ebay.com/itm/1228746-GM-OEM-ENGINE-CONTROL-MODULE-UNIT-ECM-ECU-PCM-/291959946421?hash=item43fa2b3cb5%3Ag%3AuOAAAOSwj85YQJgd&_trkparms=pageci%253A85379e17-c4dd-11e6-9c8d-0050568f4177%257Cparentrq%253A104472621590a35713b180caffeb4884%257Ciid%253A1
I hope this solves your issue. Vats disables bolth injectors so that's ruled out.
I hope this solves your issue. Vats disables bolth injectors so that's ruled out.
Well that sounds like fun.. messing with the ECM and VATs...
Well thanks a whole Tuned! Diagrams and all your info helped out. Sucks I have to change out a damn ECM. I'm sure I'll find a good thread on messing with vats and the ecm around. Thanks again Tuned!
The tps has a grey wire it to ground or the Blm wire it should be close to 5v.
The blue wire is the feedback to the ecm idle or key on it's about .54v wide open throttle close to 5v.
I don't think it's a tps issue because it's just effecting one injector.
The tps has a grey wire it to ground or the Blm wire it should be close to 5v.
The blue wire is the feedback to the ecm idle or key on it's about .54v wide open throttle close to 5v.
I don't think it's a tps issue because it's just effecting one injector.
So now inj2 not firing at all even when grounded. Had the bright idea of grounding injector two too the engine. When it worked but I guess doing that finally made injector two give out.
I switched the wires again and placed inj2 ground from ECM to inj1 and it began firing. Also placed tired the same for inj2 and nothing. Bad injector and ecm?
Okay so now I replaced my injector(inj2) with a injector from my 5.7 TBI. Mind you this injector hasn't been running for god knows how long thing had rust on the top of it and inside the tiny port where fuel goes in. I didn't even replace that filter only the bigger one.
But anyway it began to fire when I cranked over the engine. Both injectors clicking and spraying. But engine didn't start. I guess due to two different injectors spraying differently. But what if I snag a injector and my ECM is still not pulling it's weight. How likely is this situation?
If the injector was shorted the injector driver might kick off . Maybe it's flooded press the gas to the floor and crank this will stop injector pulse.
I got it fix about two three days ago. My father got feed up with me trying to fix something I couldn't fix so he went ahead and just got two rebuilt injectors. fixed the problem right up also increased my MPG.... but I got a bigger problem I crashed the damn car. entire front end is done and my crash bar bent the hell out of radiator and the thing holding it up. No cracks or leaks. car starts up and runs.... just killed the front end and maybe bent up the frame. damn it lol I'm such a idiot.
12-15-2016, 09:47 PM
