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Hey guys. A bit of background, I've been working on cars for about 10 years in shop environments and 20 years in total. This year I finally went legit and started a shop. I got a call for a guy that was broken down a few miles from my shop and he was about 1.5 hours from home. long story short, he left it with me for extended diagnosis. Initially he called stating his 1988 ranger needed an alternator. I verified the complaint, replaced the alternator and verified it was charging again. Suddenly the truck won't exceed 20-25 mph and didn't want to idle. He was able to limp it to my shop. When he pulled up I could see his exhaust manifolds glowing. The right manifold was about 80 degrees hotter than the left. I checked the plugs and the right side was indeed lean and the left side appeared rich. Once I replaced the plugs, wires and fuel pressure regulator (fuel was leaking past the diaphragm) it was able to idle. But it was backfiring through the intake still. I pulled the IAT sensor and the probe was broken off, likely from the backfires. once that all was complete, it idles fine. takes a bit of throttle to get it started but it starts, idles and gets to 55 mph with the peddle pegged in 5th. When I let off the pedal I hear some spitting and popping in the exhaust. I pulled the o2 sensor and checked backpressure with a gauge. Pressure never got higher than 1.5 psi. Vacuum at idle taken at the manifold was about 10-15 inHg and fuel pressure was 30psi. I've not been able to observe timing. The crank pully is as clean as you'd expect and I'm waiting on some white out pens to mark up the notch in the pulley. But seeing the notch shouldn't be this difficult even without whiting the notch. I'm theorizing the timing is off and contemplating rotating the distributor. I could use some help diagnosing this thing.
Edit: I also smoke tested the motor and found a gross leak at the PCV and replaced the grommet. no other smoke leaks detected. There was no pressure on the gauge but I heard it hissing trying to push the dipstick out so, for what it's worth.
Last edited by loping.chihuahua; 1 Week Ago at 09:43 AM.
If you can't see the timing marks then it sounds like the timing is off. I'm assuming you know about pulling the SPOUT jumper when doing the timing. I pulled my distributor to replace the o-ring and when I put it back together it started fine but I couldn't see the timing marks. I'm intimidated by the idea of grabbing the distributor on a running motor so I had to turn it a bit one way or the other until I could see the marks. Then it was easy to time. Basically no problem seeing the marks with the pully wiped off, down to paint.
I don't know if a bad TFI module can cause the problems you're having, but they have a reputation for going bad. Some owners carry a spare.
If you can't see the timing marks then it sounds like the timing is off. I'm assuming you know about pulling the SPOUT jumper when doing the timing. I pulled my distributor to replace the o-ring and when I put it back together it started fine but I couldn't see the timing marks. I'm intimidated by the idea of grabbing the distributor on a running motor so I had to turn it a bit one way or the other until I could see the marks. Then it was easy to time. Basically no problem seeing the marks with the pully wiped off, down to paint.
I don't know if a bad TFI module can cause the problems you're having, but they have a reputation for going bad. Some owners carry a spare.
I've only read about this SPOUT connector. Im not sure ive laid hands on it yet. I'm going to try that and try putting this thing in time throughout the week. Then I'll take a look at the SPOUT that should give me all the data I need. I also need to buy the fella an o2 sensor. I had to be a bit destructive to install the back pressure tester.
I’ll send you a photo of it tomorrow morning. I expect it looks the same on an 88 and an 89.
if the SPOUT was connected then I don’t know what you should expect for the timing marks. What you’re doing by disconnecting it is taking the spark signal away from the ECM so it doesn’t change the timing. Then you set the timing at 10 deg BTDC and tighten the distributor bolt and reconnect SPOUT. From there the ECM and probably the TFI module change what the actual spark timing is.
I’ll send you a photo of it tomorrow morning. I expect it looks the same on an 88 and an 89.
if the SPOUT was connected then I don’t know what you should expect for the timing marks. What you’re doing by disconnecting it is taking the spark signal away from the ECM so it doesn’t change the timing. Then you set the timing at 10 deg BTDC and tighten the distributor bolt and reconnect SPOUT. From there the ECM and probably the TFI module change what the actual spark timing is.
Attached is a photo of the SPOUT connector, not connected.
Do you still have the problem with one exhaust manifold getting hotter than the other, or did other work fix that? Unlike the 3.0 Vulcans, the 2.9 has the cat(s) after the y-pipe joins, so you'd expect a problem there to affect both sides. I would guess you had fuel that wasn't ignited in the cylinder burning in the manifold.
Attached is a photo of the SPOUT connector, not connected.
Do you still have the problem with one exhaust manifold getting hotter than the other, or did other work fix that? Unlike the 3.0 Vulcans, the 2.9 has the cat(s) after the y-pipe joins, so you'd expect a problem there to affect both sides. I would guess you had fuel that wasn't ignited in the cylinder burning in the manifold.
That's the one I was looking at but the diagram i was looking at looked like it was by the distributor
Attached is a photo of the SPOUT connector, not connected.
Do you still have the problem with one exhaust manifold getting hotter than the other, or did other work fix that? Unlike the 3.0 Vulcans, the 2.9 has the cat(s) after the y-pipe joins, so you'd expect a problem there to affect both sides. I would guess you had fuel that wasn't ignited in the cylinder burning in the manifold.
That's the one I was looking at but the diagram i was looking at looked like it was by the distributor. Thanks for the help. I'm going to chase it tomorrow.
i was thinking they were going down the wrong rabbit hole too. you put it out there so i just waited to see what was going to happen. nothing?
well, I still havent eliminated timing as an issue. I marked the notch on the crank pulley with whiteout and made marks at 15°± on either side of the crank notch. I cant see any of those marks while its running. So ive still got verification to do on my end but I'll get there.
It’s not clear to me what that video is or isn’t showing. Can someone clarify this?
For the record, I didn’t think timing is the root of your problem as much as thinking if you have the SPOUT disconnect and can’t see the timing marks, you must be off by more than something like 5 degrees.
It’s not clear to me what that video is or isn’t showing. Can someone clarify this?
For the record, I didn’t think timing is the root of your problem as much as thinking if you have the SPOUT disconnect and can’t see the timing marks, you must be off by more than something like 5 degrees.
the SPOUT was connected up until now. I whited up the timing marks and was going to show the state of the timing. The video I've uploaded is the timing with the spout disconnected. My timing light broke mid inspection so i dont have a video of the timing with the spout connected. I'll be back with those results.
I was referring to the video with the vacuum guage. Some of the time it looks like vacuum is dropping and other times it's staying steady. And I can't determine if "can I get some "told ya so"'s" means it shows the cats are clogged or the cats are not clogged.
I was referring to the video with the vacuum guage. Some of the time it looks like vacuum is dropping and other times it's staying steady. And I can't determine if "can I get some "told ya so"'s" means it shows the cats are clogged or the cats are not clogged.
Well, when I increase RPMs, vacuum get erratic. The vacuum reading drops like a stone. This lends credibility to the clogged cat theory. I'm checking timing as a metric to rule out the cat because i have to back pressure on the gauge I have where the o2 goes.
I wont say, "I told you so", but I did. Test it by banging on the cat with a hammer while its running. If the cat is plugged with rust it MAY respond.
We have spent more than a week discussing this. You could have had the cat off and inspected it in one day, for crying out loud!!!
You can get a useful clue with a digital thermometer, but it’s not a perfect diagnosis on its own. A clogged catalytic converter (proper term: Catalytic converter) restricts exhaust flow, and that changes temperature patterns.
How to check with a digital thermometer
Warm up the engine fully
Let the car idle for 10–15 minutes or take a short drive. The converter needs to be hot to work properly.
Locate the converter
It’s in the exhaust system under the car, between the engine and the muffler.
Measure inlet temperature
Point your digital thermometer (ideally an infrared one) at the pipe just before the converter.
Measure outlet temperature
Then measure the pipe just after the converter.
What the readings mean
Normal converter:
Outlet temp is higher than inlet (often by ~100°F / 55°C or more).
→ This means it’s actively burning off gases.
Clogged converter:
Inlet temp is much higher than outlet.
→ Exhaust is backing up and not flowing through properly.
Dead/inefficient converter:
Temps are about the same.
→ Not doing its job, but not necessarily clogged.
Important tips
Use an infrared thermometer if possible—safer and more accurate than contact probes.
Be careful: exhaust parts can exceed 500–900°F (260–480°C).
I wont say, "I told you so", but I did. Test it by banging on the cat with a hammer while its running. If the cat is plugged with rust it MAY respond.
We have spent more than a week discussing this. You could have had the cat off and inspected it in one day, for crying out loud!!!
I agree haha. I also have a day job, 4 kids and I'm a firefighter getting through emt school. But I was able to replace my timing light and the timing doesn't change the timing despite the spout being plugged in or unplugged
