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Discussion Starter · #1 ·
Hi folks.
I own a 98 chevy tracker. 1.6l, mpi, 3sp auto, 2wd, convertible. not a rocket but fun to drive. not my daily driver so I have time to play.
in the past year, it began to toggle between running really well and still running reliably but with #2 cylinder missing. chug, chug, chug :) the code i got was #2 cylinder misfire. so all new ignition parts, no change. swapped plugs, ignition wires, injectors between #1 and #2 cylinders... every time, pull the #2 spark plug and no change in engine behavior. the car then ceased toggling back to running well. so I got out my multimeter and went on a hunt. I was able to validate the injection harness on the engine from the injectors to C105 at the front of the engine and the one that runs from C105 to the ECM. I have continuity on all four injector wires and no shorts to ground. I cut the four injector wires near the ecm and inserted a terminal block for test points. from there, I used my oscope to look at the pulses. while running, the #1, #3, and #4 pulses were identical but #2 was a flat horizontal line at the bottom of the screen... dead, i think. I now blame the ecm and have pulled it. while technically capable (EE), don't see any obvious flaws in the board. nothing burnt, nothing leaking, no obviously broken or damaged traces. Any hints about what I might look for? Only operational flaw is inoperative #2 injector. Thanks in advance for any help.
 

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99 Tracker, 5 door, 2L, 4x4
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No pulse from ECU on #2, check the transistors, each FI has one.... These generally fail due to short to ground on signal line...

Sorry!, dont have a schematic.....

.....Philip
 

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Mr. Rhino would be you best bet....:rolleyes:

.... Philip
 

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Yes, Rhino will certainly be your best bet. Generally, the drivers for the injectors are just along the vertical metal plate on the side of the ECU board - you will see drivers listed as Q102-105. It is the Q103 driver that runs the #2 injector.
 

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Discussion Starter · #5 ·
Hi and thanks for your responses. i had it in mind to pull those transistors and check them. I was worried that a short might have created this but could find no evidence of such. Might redo my checks just to make sure. Thanks for the Rhinoman ref. I have gone to his website and posted a similar query there. He seems very knowledgeable. Maybe he has a tip or two. If I can't get any further, I'll likely send him my ecm. Sure would be nice to do it myself :) So, thanks for thinking about this. I'll rerun my tests and check those outputs tomorrow.
 

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Discussion Starter · #6 · (Edited)
Hi guys.
Much has happened including maybe a breakthru. Contact made with Rhinoman proved beneficial. He was patient and resourceful in helping me troubleshoot. I even sent the ecm to him for checkout. Didn't turn out to be the culprit but came back all nice and clean :) Oh, and he didn't make fun of my soldering. Thanks Rhinoman!
The ecm back in place, I tried a few things: recheck my diagnostic steps, try a bypass harness for the #2, no improvement. Then I remembered and subsequently confirmed (and should be flogged for not having checked this before) that when the harness was flexed very near plug C of the ecm, I could cause the engine to behave erratically. I smelled a clue! Exploring this, I found how to tweak the harness (more specifically, the wire for #2) just right and get the engine to run smoothly. Woohoo! Didn't stay that way though. Had to keep tweaking the wire. But one such tweak held for several minutes. So I believe I have found an offending pin but with my old eyes (i am almost 60), I can't tell how to extract it. Is there a tool for this? Replacement pins maybe? If so, I may have this beat.
 

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Hi guys.
Much has happened including maybe a breakthru. Contact made with Rhinoman proved beneficial. He was patient and resourceful in helping me troubleshoot. I even sent the ecm to him for checkout. Didn't turn out to be the culprit but came back all nice and clean :) Oh, and he didn't make fun of my soldering. Thanks Rhinoman!
The ecm back in place, I tried a few things: recheck my diagnostic steps, try a bypass harness for the #2, no improvement. Then I remembered and subsequently confirmed (and should be flogged for not having checked this before) that when the harness was flexed very near plug C of the ecm, I could cause the engine to behave erratically. I smelled a clue! Exploring this, I found how to tweak the harness (more specifically, the wire for #2) just right and get the engine to run smoothly. Woohoo! Didn't stay that way though. Had to keep tweaking the wire. But one such tweak held for several minutes. So I believe I have found an offending pin but with my old eyes (i am almost 60), I can't tell how to extract it. Is there an tool for this? Repacement pins maybe? If so, I may have this beat.
use a very fine jewelers screwdriver down the side of the pin, use a magnifying glass, theres a release clip that holds the pin in. you will probably find the wire has broken just by the crimp on the insulation and all you need to do is carefully strip it back, solder it and insulate it before returning it to service. Depending on the model, you may find a molex pin from an electronics supplier for it, but there is so many different ones to choose from, it might be easier to see if you can chop a plug off a wrecked car.
 

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Have you tested this at the connector to make sure that it is the pin, and not the wire itself. My bet, for whatever it's worth, would be either the connection or the wire, and not the pin itself.....
 

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Discussion Starter · #9 ·
Hi Bex.
In truth, it's a bit puzzling. I had inserted a terminal block about 1" downstream of the connector to have convenient test points for my scope/dvm, etc for each injector lead and have continuity between there and the accessible surface of the contact as viewed with the connector removed from the ecm. In probing the contacts with a straight pin from this open end, i have distinct resistance to movement of the pin in all but the #2. It is as if there was no contact. From that, I think this feature of the pin may be deformed and fixable but I suspect it is fatigued/broken. Just a guess. Thanks for the removal tip. I will give it a try. Failing this, I will likely configure a jumper (bypassing the connector) just for the #2. Wish me luck :)
 

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The wire end of the connector unclips and then you can use a fine jeweller's screwdriver to release the clip which is part of the connector she rather than being part of the contact. There are two sizes of contact, if you cut some connectors from another vehicle then you can practise on those, its a lot easier than when you're under the dash. The connectors are made by AMP and are very common on Japanese cars.
 

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Discussion Starter · #11 ·
ooo... again Rhinoman with the info but... the wire end of the connector unclips? meaning that the plug itself comes apart? Thanks, I hadn't noticed that. i'll have a look. Aamp is a manufacturer with which I am familiar. I will search them out. It sure was good to hear the engine run correctly. Now to permanentize it. Still have trouble SEEING that contact:)
 

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Discussion Starter · #13 ·
yet more help. Thanks. Looks straightforward. I see two rows that have wires. The lower of the two has a few open cavities. The entity that I seek to retract would be the molded nib from the top of each? and do that with a small jeweler's screwdriver. Even a caveman could do that! I'll give removing that pin a shot in a little while. Finishing this weekend with a healthy tracker would be AWESOME :)
 

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That's it exactly.
 

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Discussion Starter · #15 ·
Fixed! #2 injector dead no more.

Well... it wasn't as graceful as just pulling the pin and putting in a new one. I fought the pin removal for a while and eventually HALF a pin came out. It had broken where the wire end expands to accept the ECM's pin. Had to shove a toothpick into the ECM end of the connector and still use the jeweler's screwdriver trick but it did finally push thru. Whew! Ok, then I had no luck finding a new contact (help) so... i made a temporary one with a (drum roll) paperclip. The result? It runs correctly. I am really happy to have this thing fixed! I drove it a good bit sunday and too it to work today (about 50 mile round trip). Ran beautifully. So gotta find a contact and I can clean up the mess I made under the dash. Thanks to all of you for the help and patience. I have my buggy back.
 

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Glad you have it fixed, have done the paperclip thing myself. I have also used avionic spec quality contacts....

... Philip
 

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so... i made a temporary one with a (drum roll) paperclip. The result? It runs correctly.
With ingenuity like that, you could almost be an honorary Kiwi :lol:
 

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Thank goodness for metal paperclips. They seem to be pretty handy around here. Well done, and glad you're back on the road.
 
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