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Discussion Starter #1
ok, so I will start off by saying, this is in my Ranger. Next, this is the motor from my mustang. I recently swapped in the motor, and put a turbo coupe ecu with my quarterhorse in it. I am having a missfire problem that I can't solve. When I first put it together, it had a horrible missfire. I have done a few things that have made it less noticable, but I think it is just because it runs better, so the missfires aren't happening under as heavy a load. But I cannot get them to go away. Its not constant, or even predictable. Sometimes it does it bad at light throttle, sometimes under heavy accel. I'm lost, and ooking for guidance.

List of things done
New plugs, and regapped to ensure proper spark at .035".
New cap and rotor
Swapped out the coil with the good one from the car
Adjusted spark timing
Messed with the injector sizes in tuner
New oxygen sensor
I'm sure I forgot a few things, the only thing I haven't tried is new plug wires, but the ones I have are almost new, and have no damage anywhere.
Any ideas that might help, I'm all ears.
 

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Discussion Starter #3
87 auto tc ecu, repinned 89 ranger harness.
 

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I'd go grab a fuel pressure gauge and watch the pressure as you drive, to eliminate that as a possibility.

Make sure the PCV and vacuum hoses aren't cracked somewhere.

Might want to put the stock injectors back in temporarily and go for a road test.

I assume you swapped the TPS all ready? Try unplugging it and see how it reacts.
 

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Discussion Starter #5
Tps is the same one I had in the mustang, I took the whole motor.out, and swapped mounts then dropped it in the ranger. I do not have a set of the stock injectors, or I would have spread put them in. I'm considering a boport cam in the very near future, stage 1.5, and need to find some stock tc injectors. Also, the pcv has been eliminated, got a primitive draft tube style setup on it.

---------- Post added at 11:46 PM ---------- Previous post was at 11:43 PM ----------

Fuel pressure gauge isn't a bad idea, but I have the same setup that was in the car without this issue, and its got a better fuel pump than the mustang had. I'll give that a shot sometime. It also missfires at idle too, you can hear a stumble every once in a while.
 

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Discussion Starter #6
Update!

This is a preliminary update, as I'm not 100% sure its fixed. My egr tube has been cut off and welded shut. On the mustang I had the option to turn it off in the quarter horse. The ranger I didn't, but when I installed the motor I hooked it up. I was under the hood, and couldn't find and bad spark plug wires/loose connections so I unplugged the egr valve since I noticed it was plugged in. Then I left to go order spark plug wires and get gas. Well the whole trip it never missfired. So hopefully problem solved! I did still order the plug wires.
 

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Discussion Starter #7
Not solved... Damn.
 

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Since the issue seems to be intermittent, I'd suspect the issue to be electrically related. Are you running the Vane Air meter on that, or is it speed density? If it is running on the VAF, unplug it and note any changes.
 

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Discussion Starter #9
I am running the vam
 

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Discussion Starter #10
Update, I have noticed it does it much less if I give the truck ~10 minutes to warm up before I drive it.
 

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Discussion Starter #11
OHC I changed the plug wires, still doing it, so I unplugged the vam, drove it, still there.
 

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Have you run it with the TPS unplugged?

Verified fuel PSI? If so, I would move to wire connections; grounds, shorts, etc.

Got a known "good" TFI module, try and swap that.

Where is this thing timed, try unplugging the spout and setting 22 degrees of advance. leave the spout unplugged.

Have you read the plugs? Rich or lean? Use your tuner.

Compare stock bin file with your current tune.

Re-post with update
 

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Discussion Starter #13 (Edited)
Last time I checked the plugs they were a little black around the threads/shank but the electrode and ground strap looked like a solid stoich burn.

I am not sure on exact timing. I set it by ear, my timing light broke, so I set it and drove it, adjusted till I got spark knock, then slowly backed it off to the point where I only get spark knock under heavy load low rpm (4th or 5th gear, under ~1800 rpm)

I had the entire harness apart, i haven't found any bad wires or bad looking connections.

I have a graph of the tps signal, using the tuner i started a data record then slowly rolled on the throttle and slowly back off (automotive school training kicking in) and it looks good no bad spots i can see.

 

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Discussion Starter #15
I have not. I had considered something lime that, where did you get yours? I've never looked one up.

---------- Post added at 10:33 PM ---------- Previous post was at 10:31 PM ----------

I assume you mean the pickup inside the dist, not the module itself.
 

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Discussion Starter #17 (Edited)
I have another distributor, but its got a broken cap bolt. A lot of out stuff is the old vac advance stuff from racing.

I did buy the hall effect sensor, I haven't had a chance to install it yet, I also bought a shifter rebuild kit. Most of you wouldn't be familiar with how you rebuild a ranger shifter, lol.
 

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Discussion Starter #18
So the new pickup didn't do the trick. I think my next move is swapping the icm from the other distributor. If that doesn't work, I may need a set of stock tv fuel injectors. Anyone have a set or know where I might find a set?
 

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Discussion Starter #20
NA right now, if I boost it, it will be 6 psi. Its got the 11:1 Cr motor from the mustang in it.
 
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