Still won't run right
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Joined: Jun 2007
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Still won't run right
Here we go again. I posted some time ago about an engine problem I've been having on my 88 B ll. This bronco set for about 2 years w/ bad trans, I replaced the trans, put back the parts I had borrowed off of it for my other bronco & started it. It runs but with a miss & low power. I've checked or replaced these items. Gas tank,
both fuel pumps, distributor (put together from 2 88 blls), cap, rotor, wires, plugs, ignition coil, condenser on coil, coolant temp sensor. Took off fuel rail w/ injectors attached & turned over engine ( all injectors seemed to spray evenly), checked wiring & computer connections for corrosion. Checked & set timing, checked compression 160 to 170 all cylinders. All the spark plugs look wet when I pulled them out #s 3 & 5 look black & crusty Plus being wet, after only a short time running. Has anyone seen this before, do you think the computer could cause this or maybe because I used two distributors to make one, are there differences in the distributors? I really don't want to spend any more time or money on this, just like everybody else. Ha Any help would be appreciated, Thanks Steve
both fuel pumps, distributor (put together from 2 88 blls), cap, rotor, wires, plugs, ignition coil, condenser on coil, coolant temp sensor. Took off fuel rail w/ injectors attached & turned over engine ( all injectors seemed to spray evenly), checked wiring & computer connections for corrosion. Checked & set timing, checked compression 160 to 170 all cylinders. All the spark plugs look wet when I pulled them out #s 3 & 5 look black & crusty Plus being wet, after only a short time running. Has anyone seen this before, do you think the computer could cause this or maybe because I used two distributors to make one, are there differences in the distributors? I really don't want to spend any more time or money on this, just like everybody else. Ha Any help would be appreciated, Thanks Steve
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From: Yokosuka, Honshu, Japan
Not that the 2.9 is a powerhouse, but. Have you pulled codes at all? I am wondering if there is a vacuum leak or an EGR issue - can't remember if the '88s had EGR or not. MAP sensor would also contribute to rough running and power issues. I am curious as to what each cylinder's compression is and if there is a bit of imbalance, especially on #3 and #5. Sounds like possible blow-by or valve seals going bad. Were the spark plugs wet with gas or oil? Did you do a dry and wet compression test? Possibility exists that the plugs are too cold of a heat range or you got a bad set - if they are new. What all was replaced with new parts? Only other thing I can think of is if there is some wear in the distributor or the pickup / stator isn't 100%. On top of that, timing set (chain & gears), if they are worn and/or have slipped. All of the distributors on the 2.8 and 2.9 are the same, IIRC.
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I used new plugs wires cap & rotor, had a code for the engine temp sensor it's in the front of the intake manifold by the thermostat replaced it but the last time I ran codes it was still showing up as faulty. I did the compression test cold each cylinder was between 160 & 170. The plugs were wet w/ fuel & 3 & 5 were wet w fuel plus carboned up, after only a short period of running. This vehicle ran excellent w/ 150,000 miles on it before I parked it w/ the bad trans for two years, so it has to be something that happened while it was sitting. I tried using some seafoam in the crankcase & also let it suck about half a can thru an intake vaccum line. now it smokes like its burning oil, which it never did before. Maybe bad valve seals or just wore out, it ran so good before I let it sit, used about half quart of oil between changes. I'm debating pulling the motor apart, just want to make sure something in the engine management system isn't causing this problem . It really doesn't make sense, good compression, good spark, & fuel, should run, I miss carburetors, they had their problems but it didn't take a basket of money to get one going. Steve
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From: Yokosuka, Honshu, Japan
Was it the ECT or IAT sensor that came up? There are two sensors for temp, one for coolant, the other for intake air temp. I believe you have to clear the computer memory after a sensor is replaced and then do a KOEO and KOER to re-check. I will venture to say more than likely the valve stem seals are dried up and cracked. With compression where it's at, I don't think you'd use much oil, other than leaks - 1/2 a quart between changes sounds more like a leak than blowby on the oil control & compression rings. While it was sitting up, was it started up at all? I am going to venture at guessing it sitting might have added a little to the problem(s) - if the engine isn't run, the rings tend to do strange things, but it sounds like they are fairly intact. I will venture to say the difference in compression is more valve stem seal related. Wouldn't hurt to change out the seals and re-re-check your codes.
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Joined: Mar 2009
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From: Columbia, SC
Valve stem seals has nothing to do with compression, all a valve stem seal does is just what its name says, it seals the valve stem so oil wont get by and end up getting burned. now a bad valve seat would affect compression, bad rings, hole in the top of a piston ect... with compression range 160-170 sounds good. sounds like its running rich and that would point to possible O2 sensor problem.
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From: Yokosuka, Honshu, Japan
I guess I was taught wrong, then - the reason for doing a 'wet' compression check, that is... to differentiate whether it's the rings or the valves/valvetrain to include valve guides -and- seals. *shrug*
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Now if you're thinking a cylinder LEAK-DOWN test? While the valve seals are normally El'Cheapo rubber, this test will point towards burnt valves, cracked seats, and bad rings. Just put the cylinder to TDC on the compression stroke, apply air with a special fitting...and use the ears to listen for where the leak(s) are.
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Posting Guru
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From: Yokosuka, Honshu, Japan
Heh. Forgot about that, Tedy. Sometimes I have so much information in my head, it gets all screwed up. Had a leak-down confused with wet/dry compression test 
Thanks for the clarification 
Thanks for the clarification
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From: Yokosuka, Honshu, Japan
I hear ya. I have a buttload of work on my '87 awaiting me when I finally get back to the States. It may have developed a clogged drain on the cowl vent (gotta love East Texas Pine needles!) - seemed like the floorboards were a little wet back in December when I was on leave, and I didn't notice any coolant loss. I didn't have time to check it out and clean out the interior. Hopefully, I don't come home and have to deal with an extremely rotted out floorboard I also have some troubleshooting to do and part of it may include replacing vacuum hoses and pieces and parts of the EGR system. Plus, I have a few project things to do to it, various mods. Not sure if I am going to put my Early Bronco axles under it or not, as I have a line on an '84 with a chopped top that would be more fun to build up for mostly off-pavement driving. Might end up doing a D35/8.8 swap on the '87. I guess we'll see 
I also have some troubleshooting to do and part of it may include replacing vacuum hoses and pieces and parts of the EGR system. Plus, I have a few project things to do to it, various mods. Not sure if I am going to put my Early Bronco axles under it or not, as I have a line on an '84 with a chopped top that would be more fun to build up for mostly off-pavement driving. Might end up doing a D35/8.8 swap on the '87. I guess we'll see
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