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IDFK What's going on with my 2.9l. Starts and runs fine when cold, when warm it jerks and starts with misfire... sometimes.


McWillies

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She's back up and running. After some confusion I got the 2nd head on Monday and got everything pretty much done by yesterday evening. Was having some issues getting the distributor to sit right then I read online and figured out the oil pump shaft is what was holding me up. Got everything set right and the distributor dropped in. This morning set the timing and took it for a test drive, went great. No overheating, oil pressure was perfect. While it was idling I noticed the PCV valve going crazy and after looking at it I found a crack in the upper plastic portion (elbow). Got that replaced and now it's idling smoother. Haven't taken it on a very long test drive so I'll do that in the morning.

Here's a few pictures of the Promaxx head, it's definitely a quality product. Might be difficult to notice the improvements from the original castings, but I gave them a good eyeballing side by side and there's definitely more meat in various places:
On this first picture if you look closely to the left of the rightmost spark plug hole you can see a casting date printed on it. Also no Ford casting numbers on it, so it's definitely a new unit.
15057
15058
15059
15060


And now here's a picture of the final product. I cleaned everything that I had off but you can hardly tell because it all got covered up by the wires and hoses. Worth it either way to have the shiny intake and the little bit of blue showing through.
15061


Lastly I want to thank everyone so far that has helped me through this process. Definitely would be lost without the RBV forums and the tech libraries.

Edit: Forgot to mention, the pistons in the block were mahle with a 03/89 prod date stamped on them, and an 828 model number. Looked at the casting number on my block and it's an 89TM. Question: I know it's common for people to say that the newer style heads are 89TM and the older style are 86TM, but I had one of each on my engine and they were both stamped 86TM... Is it true that all heads were stamped 86TM and it was actually the stamp on the block (87TM/89TM) is what actually determines the heads it came with?
 
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McWillies

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Some good news! Drove it back to my apartment, about an hour and a half, and it ran great. It's so quiet now with exhaust manifold gaskets and having the manifold to y-pipe flanges tightened up, I get worried it's died on me when I stop at a light :icon-rofl:. Temps stayed perfect the whole way and I had the a/c on full blast (it's hot and humid here in Louisiana). One thing I did notice is the compressor clutch kicks on and off at idle, causing the engine to surge (doesn't have enough time to compensate for the compressor being on). I'll check the refrigerant level and add some if need be. Truck feels better than ever, I'm very happy with it. Now I gotta fix all the air leaks into the cab when I'm on the highway because there's no loud exhaust leaks and engine noise drowning it out. Thanks again for the help everyone. Specifically @JerryC, you've helped out a lot, appreciate it sir.
 

JerryC

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It does sound like you're just a touch low on refrigerant.
I'm happy to have helped.
 

Nelson and Hudson

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And when it is running well, what kind of fuel usage (MPG) are you seeing?
We JUST got ours running and it is a little under 10 MPG right now.
 

JerryC

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I just topped off mine, during the snow storm a couple of weeks ago. I used about half a tank. 121 miles, about half in the snow and another 25 or so with the hubs locked because I forgot to unlock them. 12.5 MPG.

About 15 miles of that was with the front diff pushing snow. I could not go faster than 20-30 mph or the tires would spin and it felt like I was dragging an anchor behind me. That was the most fun I've had since I bought it. This was the only year I NEEDED 4wd so far. I actually got stuck in 2wd.

I usually get ~14mpg doing little 5-10 mile trips. When I used to just ride around the country roads an hour at a time I would get near 18mpg.
 

XTC90BII

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That is generally what I get Jerry when I am just driving back and further to town every day which is 10 miles each way. About half in the city and about half on open road. So I get around 17.5 to 18.5. If I take it to Tulsa or KC and run around the 65 MPH mark it I get around 24 or 25.

Dennis
 

wildbill23c

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Some good news! Drove it back to my apartment, about an hour and a half, and it ran great. It's so quiet now with exhaust manifold gaskets and having the manifold to y-pipe flanges tightened up, I get worried it's died on me when I stop at a light :icon-rofl:. Temps stayed perfect the whole way and I had the a/c on full blast (it's hot and humid here in Louisiana). One thing I did notice is the compressor clutch kicks on and off at idle, causing the engine to surge (doesn't have enough time to compensate for the compressor being on). I'll check the refrigerant level and add some if need be. Truck feels better than ever, I'm very happy with it. Now I gotta fix all the air leaks into the cab when I'm on the highway because there's no loud exhaust leaks and engine noise drowning it out. Thanks again for the help everyone. Specifically @JerryC, you've helped out a lot, appreciate it sir.
Yep, AC is most likely low on refrigerant. It'll cause rapid cycling of the AC compressor. If it hasn't been converted to R134A, you'll have to do that before you add refrigerant. Grab an adapter kit, a vacuum pump, a gauge set, and refrigerant evacuate the system, then put the system under vacuum and let it set about 1/2 hour to an hour then check the vacuum at the gauges again to see if you have any leaks, if so, you'll have to find the leaks and fix that, then recharge the system....no you honestly don't need to change the compressor, evaporator, condenser, hoses, etc. to go from the old R12 to R134A. You can if you want to. I did the adapters on a 91 Ford Tempo a couple years ago, vacuumed the system down, checked for leaks, fixed a couple recharged the system and its been fine without changing out any other parts just added the adapters to hookup the hoses.
 

wildbill23c

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I just topped off mine, during the snow storm a couple of weeks ago. I used about half a tank. 121 miles, about half in the snow and another 25 or so with the hubs locked because I forgot to unlock them. 12.5 MPG.

About 15 miles of that was with the front diff pushing snow. I could not go faster than 20-30 mph or the tires would spin and it felt like I was dragging an anchor behind me. That was the most fun I've had since I bought it. This was the only year I NEEDED 4wd so far. I actually got stuck in 2wd.

I usually get ~14mpg doing little 5-10 mile trips. When I used to just ride around the country roads an hour at a time I would get near 18mpg.
I usually get around 12-14mpg around town depending on the time of the year. Winter its lower as I have to warm the thing up before I can drive it, kind of hard to see where you are going when there's ice on all the windows inside and out LOL. In the summer its lower because of the AC usage. On a good day and long trip I can get 18-19mpg. Before I put the 235/75-R15 tires on it, I'd get around 15mpg in town and 20-21 on the highway....larger heavier tires screwed the fuel economy, but I'd rather have the better tires than negligibly less fuel economy overall. I don't drive the Bronco 2 much out of town so fuel economy is irrelevant. My 87 Ranger gets 21-23mpg in town and 24-25mpg on the freeway but its a bare bones basic 2wd pickup with manual transmission and 2.9L V6, hardly any weight for it to move around. Probably could squeeze 26+mpg out of it on the freeway if I wasn't driving the 80mph speed limit, if I went down to 70-75mph it would probably easily get 26+mpg. In town I was surprised it was getting 21-22mpg in the winter, once the weather warms up I see 23mpg quite often though in town, the manual transmission and light weight helps a lot. Plus it has 14" wheels and stock size tires which don't weigh much either LOL.
 

McWillies

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Vehicle Year
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Vehicle
Ford Bronco II
Engine Size
2.9l
Suspension Style
4wd
Yep, AC is most likely low on refrigerant. It'll cause rapid cycling of the AC compressor. If it hasn't been converted to R134A, you'll have to do that before you add refrigerant. Grab an adapter kit, a vacuum pump, a gauge set, and refrigerant evacuate the system, then put the system under vacuum and let it set about 1/2 hour to an hour then check the vacuum at the gauges again to see if you have any leaks, if so, you'll have to find the leaks and fix that, then recharge the system....no you honestly don't need to change the compressor, evaporator, condenser, hoses, etc. to go from the old R12 to R134A. You can if you want to. I did the adapters on a 91 Ford Tempo a couple years ago, vacuumed the system down, checked for leaks, fixed a couple recharged the system and its been fine without changing out any other parts just added the adapters to hookup the hoses.
It's been a few months but I had already converted to r134a at this point, thanks for the info boss.
 

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