Having weird power issues with my '88 2.9

[DisturbedMXer8]

Replaced my MAP, and the problem still persists. It actually seems to be getting worse (affecting my accel), but that could just be in my head, it's not at all severe or anything. It does run much better cold with the new MAP, though. I installed it on a cold day, and while driving it around town that night it seemed to have fixed it. Problem is still there though, noticed mostly while driving home from school around noon. I am completely stumped, no idea where to go from here.

Does the computer use RPM at all to determine fuel? Today, it would instantly clear up at 2500, instead of 3k like normal. It almost seems like a tach issue, if the computer used it at all (dash tach works perfectly fine, though).

I'll definitely replace the plastic lines. Not too many of em on there anymore, but I feel I should get rid of all the old vacuum lines and get new ones for my Truck's "birthday".

 

[jay jigless]

you should try cleaning your fuel system with some lucas fuel injector cleaner if you havent already and for the TPS if you havent changed it yet you can clean it with some carb cleaner if it looks black or just plain ol' dirty and/or you should try and replace the air intake sens. it is about $100.00 @ autozone, or it should be pretty cheap at a salvage yard. but if you do buy it brand new then you should take the two screws out that are holding the air cage and the CPU together and put a lil anti-seize on it for later cleaning. if you have done absalutly everything to that motor and it is still f*cking up then try replacing it. $100.00 dollars at a LKQ salvage! you would have alot of new parts already. well i hope that i have helped you out.

 

[DisturbedMXer8]

you should try cleaning your fuel system with some lucas fuel injector cleaner if you havent already and for the TPS if you havent changed it yet you can clean it with some carb cleaner if it looks black or just plain ol' dirty and/or you should try and replace the air intake sens. it is about $100.00 @ autozone, or it should be pretty cheap at a salvage yard. but if you do buy it brand new then you should take the two screws out that are holding the air cage and the CPU together and put a lil anti-seize on it for later cleaning. if you have done absalutly everything to that motor and it is still f*cking up then try replacing it. $100.00 dollars at a LKQ salvage! you would have alot of new parts already. well i hope that i have helped you out.

Well, if by air intake sensor you mean MAF, I don't have one. They didn't start using those until 89 or 90 I think. As far as the TPS goes, I'm pretty sure they are adjustable on the 88's and earlier, so I'm afraid to mess with mine or get a new one for fear of ruining the adjustments.

 

[Caps4x4]

Take the CAT out and go run it, I've had plugged CATs in the past do very, very strange things to driveability. Does the 88 use a vacuum advance for the timing?...

 

[DisturbedMXer8]

Nope, electronically advanced with the TFI. I'm going to ask a few Ford tech's their opinion on the subject, and if I still can't figure it out I'm just going to have to take it in. It's been steadily getting worse and worse, and I'm running out of patience.

 

[Caps4x4]

ahh. I've had the TFI cause a stall before, but never a power loss like you're talking about.

 

[copperminer2002]

Under the air box, there is a tube that feeds air up thru the bottom of the filter box. If this thing has been setting for nine years, there is a good chance that mice may have built a nest in this tube. That happened to mine, and when I cleaned it out, it ran much better. I live in the desert tho, and we have a lot of mouse issues. Nests, and chewed wires mostly. lol

 

[DisturbedMXer8]

Haha, yeah, I've heard of that happening before. No mice for me, though. It hasn't always been like this, it started doing it a few months after I got it (sometime in june-july). The thing is, I need a lot of suspension work (new shocks, bushings, bearings, etc...), so I really don't want to have to take it in to figure this out.

 

[Crashtest84]

After reading this I am having the same problems with my 89. Runs fine until your just trying to slowly speed up or in high gear on the hwy. Things I have done to mine since I got it a week ago have been new plugs, wires, cap, rotor, air filter, can of seafoam in the tank new fuel filter going on in the morning and needs exhaust. I had to put a new starter on it today, while I was changing that I saw a sensor in the lower part of the engine block " drivers side" that has nothing plugged into it looks to be maybe a knock sensor. Anyone know what im talking about I will let you know if I ever get my problem figured out

 

[IMenriched]

After reading this I am having the same problems with my 89. Runs fine until your just trying to slowly speed up or in high gear on the hwy. Things I have done to mine since I got it a week ago have been new plugs, wires, cap, rotor, air filter, can of seafoam in the tank new fuel filter going on in the morning and needs exhaust. I had to put a new starter on it today, while I was changing that I saw a sensor in the lower part of the engine block " drivers side" that has nothing plugged into it looks to be maybe a knock sensor. Anyone know what im talking about I will let you know if I ever get my problem figured out

pretty sure that sensor would be the knock sensor


Ok really get a sense like these are more vacuum issues.....slight ones where you're not down terribly.....but just enough where as you press on the gas slightly ...say like going up a little incline as your going down the road 60-70mph...& you need a bit more uummph, to keep pace...& the engine just lays there, kinda laboring to pull itself. BUT if you tap the gas harder(3/4 or more pedal), it kicks down and away you go.


Or could this be a timing thing where the timing is at or near maximum in those situations as described earlier....say like going up a little incline as your going down the road 60-70mph...& you need a bit more uummph, to keep pace...& the engine just lays there, kinda laboring to pull itself.

for those with greater knowledge than I.....What is maximum timing advance?

 

[DisturbedMXer8]

Ok really get a sense like these are more vacuum issues.....slight ones where you're not down terribly.....but just enough where as you press on the gas slightly ...say like going up a little incline as your going down the road 60-70mph...& you need a bit more uummph, to keep pace...& the engine just lays there, kinda laboring to pull itself. BUT if you tap the gas harder(3/4 or more pedal), it kicks down and away you go.


Or could this be a timing thing where the timing is at or near maximum in those situations as described earlier....say like going up a little incline as your going down the road 60-70mph...& you need a bit more uummph, to keep pace...& the engine just lays there, kinda laboring to pull itself.

for those with greater knowledge than I.....What is maximum timing advance?

Yeah, that's pretty much the only other thing that makes sense to me. I don't understand why my timing would cause this all the sudden though, when I know it's always been the same. Since I only have power up top, maybe the timing isn't advancing at low RPM like it's supposed to? Like it's stuck where it's supposed to be at WOT (retarded, if I'm not mistaken). I don't know if that's even possible with electronic ignition, but just something I thought about.

Vacuum would also make sense, since I noticed it's worse (although not horrible) when I applied throttle. Like you said, maybe it's enough to cause issues at higher speeds and lower RPM. I just wish I knew how to find these things out, haha...

 

[IMenriched]

Yeah, that's pretty much the only other thing that makes sense to me. I don't understand why my timing would cause this all the sudden though, when I know it's always been the same. Since I only have power up top, maybe the timing isn't advancing at low RPM like it's supposed to? Like it's stuck where it's supposed to be at WOT (retarded, if I'm not mistaken). I don't know if that's even possible with electronic ignition, but just something I thought about.

Vacuum would also make sense, since I noticed it's worse (although not horrible) when I applied throttle. Like you said, maybe it's enough to cause issues at higher speeds and lower RPM. I just wish I knew how to find these things out, haha...

Did you go with after market MAP sensor?? I was wondering if some of the aftermarket ones are made with generic settings internally...where the 2.9 and its ECM need to have more specific set of signals to run by??.... like the situations you and others are experiencing. just a random thought. According to google search, the map sensor is more for idle....but it has to play a part in the cruising rpm range as well...so that timing changes as one applies the right pedal or releases it to slow down.

 

[DisturbedMXer8]

Did you go with after market MAP sensor?? I was wondering if some of the aftermarket ones are made with generic settings internally...where the 2.9 and its ECM need to have more specific set of signals to run by??.... like the situations you and others are experiencing. just a random thought. According to google search, the map sensor is more for idle....but it has to play a part in the cruising rpm range as well...so that timing changes as one applies the right pedal or releases it to slow down.

Well, I guess it's considered "after market", but it's nothing performance or anything different than stock. It's just the OEM spec Duralast that they had at Autozone, and it's supposed to "Meet or exceed OEM performance", so I assume it's the same as the original one. To be 100% honest, since my problem is intermittent, it's safe to say that I really didn't notice any difference with the new MAP sensor. I don't think it really changed much, if anything at all.

 

[Crashtest84]

well, to update you on a lil of what I have found. I pulled the drivers side valve cover to try and adj the valves a lil as I have a pretty bad lifter tick. I had two rockers that were loose. So I tighten them down and started the truck with the cover off and not only did I have a very bad tick still, I also had no oil at all out of the rockers.

My general idea is without the oil to pump the lifters up im not getting full lift of the valves at the lower rpm speeds hints low power and slight miss feeling. So tonight when I got home I pulled the rocker rail and what do you know its full of crud. Can anyone tell me if im right with the oil flow here.. starts with the oil pump to filter to the mains and rods from there to the cam and from there does it feed the lifter galley or does it go the the rockers then just kinda oilbath the lifters? Anyway right now im soaking the rail in the parts washer to clean it out and start over again.

Maybe this will give you another idea to look for on your truck oh and I did a compression check be for I did anything and its 170 psi give or take a few on all cylinders

 

[IMenriched]

well, to update you on a lil of what I have found. I pulled the drivers side valve cover to try and adj the valves a lil as I have a pretty bad lifter tick. I had two rockers that were loose. So I tighten them down and started the truck with the cover off and not only did I have a very bad tick still, I also had no oil at all out of the rockers.

My general idea is without the oil to pump the lifters up im not getting full lift of the valves at the lower rpm speeds hints low power and slight miss feeling. So tonight when I got home I pulled the rocker rail and what do you know its full of crud. Can anyone tell me if im right with the oil flow here.. starts with the oil pump to filter to the mains and rods from there to the cam and from there does it feed the lifter galley or does it go the the rockers then just kinda oilbath the lifters? Anyway right now im soaking the rail in the parts washer to clean it out and start over again.

Maybe this will give you another idea to look for on your truck oh and I did a compression check be for I did anything and its 170 psi give or take a few on all cylinders

compression pressure is most excellent.

yes oil flow and pressure to the top end of the 2.9 is a issue with this engine. If you have any kind of miles on it...it most likely is due to worn cam bearings, or they are a major contributor anyway, next is worn main and journal bearings, and yes a weak oil pump compounds the whole chain of events. cheap oil filter can also be on the list too.

you might be wise to pop out the end cap of the rocker shaft and clean the inside of it... Also, check to see if the the cam bearings have rolled inside the block....crank it over some with rocker assembly off to see if you're getting oil to the top or not. the cam bearings at (#2 &#3 bearing) are suppose to have oil port in them...if they roll it could have blocked oil or partial blocked oil from continuing on.