HELP! low power, rough idle issues

[fairman86]

hey guys, i have a 98 mazda b2500

just did the timing belt on it, timing marks are all aligned, truck will start usually with out a problem, but when cold has one hell of an idl issue, it will acually shake the truck. when you blip the throttle it will knock then rev, if you go slowly into the throttle it struggles for the first 800rpm then smoothes out and will rev pretty good above 2000 rpm, while cold if you rev it up to about 3-4k rpm and let off it will retun to barely an idle knocking and shacking sometimes stall sometimes sort itself out. once warm it seems to idle fine while just putting around town no faaster than 60km/h

i tried to take it on the highway today and on ramp in third it is pretty slow to hit 80, then 4th to go above 100 is quite the stuggle, if i put my foot harder into the throttle it dosnt really pull any harder. to maintain highway speeds its pretty sluggish, then once i come off the highway and come to the first stop sign on thw off ramp, it barely idles and stalled, but fired right back up and with a little convincing it ran smooth again, and puttered around town no poblem not going above 60km/h


i have taken out and cleaned the map sensor, i have a new egr tube, i tried taking the vacuum tube off the egr valve and plugged it, seems a little better but still does the same stuff. i ran a scan tool, im not sure what it means but it says my "short term" fuel was at 33 and my "longterm" fuel was at 3. i am going to put a new fuel filter on it tonight and pull the tps and clean it, any other suggestions?

 

[fairman86]

i'm also supposed to be leaving tomorrow morning for a camping trip with my dirtbike and gear, so if it barely runs the highway without a load, then it wouldnt be much good with a load. any help would be geatly appriciated! thanks

 

[fairman86]

just to be sure, the timing marks line up as they should, the triagle lined with the triangle the diamond lined wit the diamond and the keyway at the top

 

[Rogue_Wulff]

Triangle to triangle, diamond to diamond, yes. I don't think the crank lines up with the keyway straight up though. There's a mark on the gear that lines up with a notch on the engine, or just line up the balancer mark with the "0" (TC) notch in the cover.
http://www.therangerstation.com/Magazine/Summer2010/4cyl_timing_belt.htm
Kinda sounds like how my truck ran when I got it. PO had lined up the dimples on the rear belt guides with the triangle/diamond on the cover. Cam was 5-6 teeth advanced, and the oil pump/cam pos sensor was ~120* off.

 

[fairman86]

well just to be sure ill re-recheck it, lol i ended up putting a new fuel filter on it and an air filter and seafoaming my sensors and engine, that thing was DIRRRRTY! the fuel filter was caked with rusty mud looking gas, and the thing tossed so much smoke when i seafoamed it, i had people asking me if i just blew my motor, lol... its running ALOT better now, still has an idle issue, seems rough 90percent of the time but isnt overall that bad. and when its cold it seems to have more power. only thing is if its cold and i speed up quickly then push in the clutch, the engine will die, and takes a couple tries to get it started again..thats only under a quick hard acceleration ive also noticed that while driving around slowly in reg traffic,up to reg operationg temp, i'll shift into second and go to accelerate and the truck wont.. it just bogs and very very slowly comes back to life. if i push in the clutch and rev it its come right back. its only happened 2 times. the truck is a lot more powerful than it was before cleaning the engine and changing the fuel filter. i have also put a can of seafoam in my gas tank, ive pretty much gone through that gas now from the trip up north, but i might put another through it to make sure my fuel system is good and clean. now im really not sure, but i have put 31" tires on my truck, and i find that unless completly empty (load wise) and not going up hill i cant use 5th/OD i usually stick in 4th cruising on the highway at 90-100km/h but on the freeway im back and forth from 4th to 5th from 100-130 km/h is this normal for the 31" tires and i think 3.83 gears? what i can remember second will do 80km/h stretched out. i know alot of you with 31" or bigger tires have opted to switch out for the 4.10 gears, is this all im lacking? can it possibly be the answer im lookin for? this thing seems like it has no top end.

 

[tbirdsps]

Did you test the fuel pressure with a gage? I'm thinking 39-40 at idle. If you filter looked that bad imagine what the fuel pump looks like.

 

[fairman86]

yes this crossed my mind, i havnt checked the fuel pressure yet, been very busy with work now that im back from my trip. i can only imagine what the inside of the tank looks like, i know its plastic, BUT the didnt think to make the filler neck rubber or plastic, but instead they made it steel, thus for all the rust in my tank. so ill be replacing the tube to prevent more rust from going into my tank. so ill check back once i test the fuel pressure, so about 40psi for idle, then whats it spike to?

 

[fairman86]

bump....

anyone know the fuel pressures? 40 at idle then what is the max it should read, also while shifting between gears the idle will spike to 3-4000 rpm stay there anywhere from 2secs to 15 secs then idle down on its own, if i slap the throttle while its high revving It'll rev a little higher then after about 2 secs it will return to reg idle rpm. when first started it has somewhat of a rough idle that shakes the truck then calms itself down after its done chocking itself, and its def getting too much fuel, so with these symptoms I'm guessing TPS or IAS but what do you think?

 

[fairman86]

bump bump bump..