4.0l wont rev up well.

[comanche12]

Yesterday, its been snowstorm so I was began dying to test my comanche's 4x4 so I decided to do it! 4x4 works great!

 

Well but during last night after test drive, i left it outside so i can paint the hitch for my friend's impreza in the garage. So, I'm gonna put my MJ back in garage. I let the engine warming up. After little warm up, I rev up engine gently and its rev up smooth but after good warming up, I did rev up again to compare the little colder temp and operation temp-

engine won't rev up to about 4500, its choked(sputtering) on like 2-3k then upshift light blink but its in neutral then finally rev to 4500 then choke again :???:

 

the choke issue did occur same thing when I was drove my mj around. :hmm:

 

Check the tps and map? I'm don't have good knowledge with MAP compare to MAF though.

 

-87 4.0l with ba 10/5-

[comanche12]

well I actually just checked TPS, MAP and IAC.

 

TPS read 4.88v from wire(lt blu) that applied 5v and .3v from the inputput wire to ecu(yel/grn) so i adjusted the tps to make the input wire read from .3v to .8v and test it by maunal open the throttle body blade to make sure it read fine. its read up to 4.88v perfect

 

After TPS, I checked the MAP vacuum hoses and its was noticeable loose on the TB port so I push the vacuum back into the TB proper.

 

Afterward, I decided to removed the Idle Air Control or whatever its called, its pretty cover with build up of carbon, cleaned it out with the carb cleaner and plugged IAC back on the TPS piece of cake.

 

I havent started my engine to test the issue again since its get late so tomorrow ill do it.

[comanche12]

I just started my mj up. let it ran until warm up. After about 180*F, checked the MAP vacuum hose again- everything is fine, so I rev it up. engine is still choking on about 2-3k its like it have misfire, run lean, mistiming on ignition, etc. :(

 

its like ecu won't let me rev up while floor it. only able be smooth while gentle rev engine up.

 

 

maybe check fuel pressure? rent pressure gauge from autozone? check the ignition(advance/retard) time? :hmm:

[Geonovast]

Timing is not adjustable.

 

I think you're making it too complicated. Check the dist cap, rotor, wires, and plugs.

[comanche12]

Timing is not adjustable.

 

I think you're making it too complicated. Check the dist cap, rotor, wires, and plugs.

 

i though we can adjust by do to rotate the dist? my bad and ill check it out asap. thanks for quick reply

[comanche12]

i just tested the sparkplug wire, they r within the spec so i pull the cylinder 3 sparkplug where its most easy to reach... haha

 

so i looked at it, its look in good shape and look like new but havent measure the gap. i lost my measure for the gap :doh:

 

but here reason i post this is because i just notice that this sparkplug is Bosch platinum plus... don't those brand sparkplug tend have problem with ignition as i remember?

[Pete M]

nope. if you did manage to turn the distributor (there are tabs on it that prevent this), the computer would just try to re-adjust back to what it wants. :thumbsup:

[Mike Stone]

bosh is JUNK!! go to champion plug. replace cap and button.

[Geonovast]

What is "within spec" on the spark plug wires to you? I don't consider them good unless they're under 1 ohm.

[comanche12]

bosh is JUNK!! go to champion plug. replace cap and button.

 

 

knew it! knew it! :grrrr: i was thinking about buy champion plug too. but why cap and button too? they look good in shape though? :dunce:

[comanche12]

What is "within spec" on the spark plug wires to you? I don't consider them good unless they're under 1 ohm.

 

iiroc from alldata with info about 4.0l spec- quoted from all data:

 

Minimum 250 ohms per inch (3,000 ohms per foot)

Maximum 1,000 ohms per inch (12,000 ohms per foot)

 

one of my wire that i measures is about 300 ohms and the wire is about 6 inches

 

 

edit: i just read it again. its said per inch :doh: so its should be about 1200 ohm for 6 inches wire?

[Geonovast]

You only checked one?

 

And I think I meant kOhm. :hmm:

[comanche12]

yea I'm gonna check other too anyway. I'm just take time and no need rush.

 

nah 3xx ohm. my meter said about .3xx kohm

[Geonovast]

yea I'm gonna check other too anyway. I'm just take time and no need rush.

 

nah 3xx ohm. my meter said about .3xx kohm

 

300 Ohms is .300 kOhms

[comanche12]

yea I'm gonna check other too anyway. I'm just take time and no need rush.

 

nah 3xx ohm. my meter said about .3xx kohm

 

300 Ohms is .300 kOhms

 

thats what i said... lol I'm gonna check other wires now ill let you know whats their resistance is, asap.

[comanche12]

ok i pulled one about 10 inches and resistance is...... about 7.77kohm which is about 7,770 ohm

 

that wire passed as its within the spec

[Geonovast]

If you can afford it... since you're changing plugs anyway, do everything. Cap and rotor should be under $20, plugs should be about $12 for all 6, wires can be had for $15-16.

[comanche12]

i wish i could afford it. I'm already saving money for rear brakes. its still driveable. that issue only occurs if i floor the gas.

 

 

thanks for your help! its sound cheap to me but gotta get rear brakes first.

:cheers:

[Geonovast]

Don't forget to check your fuel pressure.

[comanche12]

yea thats what i was thinking. thanks to remind me man :thumbsup:

 

does autozone offer rental for pressure gauge to test the fuel pressure?

[Geonovast]

I wouldn't know about autozone, but O'reillys is pretty good about that stuff. They usually won't even do a deposit if you use it in the parking lot.

[comanche12]

one more question, which champion should i get? copper or plat.?

[Pete M]

plain ol' copper works great in our engines. :thumbsup:

[comanche12]

plain ol' copper works great in our engines. :thumbsup:

 

 

haha thats what i though which reason i asked first. thanks pete! :thumbsup:

 

I wouldn't know about autozone, but O'reillys is pretty good about that stuff. They usually won't even do a deposit if you use it in the parking lot.

 

no problem thanks again

[J B Cuz]

if the motor runs fine at low rpm but dies on the high end it sounds to me like a lack of fuel. The other reason to not look at the plugs is it is running well at low rpm so why would the ignition system only fail at high rpm. Change the fuel filter see if that fixes it.

 

J B Cuz