Idles Fine but when you touch the throttle it sputters all over the place

Ive been lookin this up and everyone thats posted about this either doesnt have the complete same problem or didnt resolve theres. I have an 89 4.0 and about 2 weeks ago it stopped running. We replaced the coil, distributor and finally replaced the CPS ( crank positioning sensor ) and that fixed the problem. but now it starts fine and idles ok but everytime you touch the gas it sputters all over the place and has zero power. The jeep ran great before it stopped and i had no problems with it. I kept thinking it had to be timing but me and my friends have retimed that thing soooooo many times that were convinced thats not it. We put it to TDC and lined the rotor up with #1 cylinder at least a douzen times and nothing changes. we replaced the TPS and that didnt do anything either. I have enough fuel pressure. Im about ready to say screw it and sell it. can someone please help

Did you adjust the the TPS once you installed it?

If it's miss adjusted, then you will have problems.

Both the CPS and the MAP sensor can make it do that. Check the vacuum tube for the MAP sensor.
Do a resistance test on the CPS, if the resistance gets way high (around 200 ohms) it can do this.
Adjust your TPS, make sure you are adjusting the correct half, if you have an automatic. The TPS has a lot to do with timing, the distributor actually has less.
The CPS connectors have to be clean, with little resistance between the CPS and the ECU. Any significant resistance in the connectors or the harness can cause this. Check the grounds at the dipstick brace.
Make sure your CPS is mounted correctly. The distance from the pickup end and the tone ring is critical. It's tight in there and easy to think the CPS is seated correctly when it isn't. If your replacement CPS has a slotted bolt hole, it has to be pressed down (towards the tone ring) during tightening.

Sounds like you knocked the vacuum line loose at the bottom side of the throttle body that feeds vacuum to the MAP sensor, if your lucky that is all it is.

Where did you end up with the rotor cap pointing while at TDC compression stroke? haynes and some online lists have it a t 6 o'clock, but it should be at 5 O'clock.

Also check the coil to dizzy HV wire for damage during all the dizzy resetting work. That's about all I can add to 8muds good list below.

thank you everyone im gonna give these things a look over and see what i come up with

i know this is gonna sound absolutely retarded, but is your dizzy in right?
i know a guy who had his 180* around. somehow, it idled just fine, but as soon as you gave it gas it sputtered and died. it too was an 89, btw.

"We replaced the coil, distributor and finally replaced the CPS ( crank positioning sensor ) and that fixed the problem."

if you replaced them all at once i would agree you should check for "dizzy" indexing.

You stated you put the engine on compression stroke for cylinder #1 then lined up the rotor. I may be stating the obvious, but you know you don't have it pointing right at the terminal, right? In actuallity you need to have the engine set to about 15 degrees before TDC if it is pointing right at the post in the cap.

Other things that can cause what you describe are a bad TPS. Check the supply voltage to the sensor and that the output changes smoothly if you grab the little arm and rotate it. I have seen TPS's installed with the arm on the wrong side of the actuator. Rotate the throttle shaft just as it would if you pressed down on the gas and make sure it causes the TPS arm; to rotate. I am not familiar with the arm configuration on the HO so forgive me if you have an HO.

Don't give up. As a last resort, PM me and I will give you my phone and we can talk directly.

A thought just went through my head. If you were wheeling, you may have crushed the exhaust causing a lot of backpressure. It would idle but crap out at any higher rpms. You can verifiy that or a plugged CAT with a vacuum gauge.

That symptom is exactly what I had when the distributor indexing was off by one tooth retarded on my 87. Mark the present location of the rotor, and try getting it one tooth further advanced.

Matthew Currie said:

That symptom is exactly what I had when the distributor indexing was off by one tooth retarded on my 87. Mark the present location of the rotor, and try getting it one tooth further advanced.

Click to expand...

Oldman,

Regarding the 15 degrees BTDC on the compression stroke, as I recall there just something like 16 gear teeth on the dizzy (I forget the exact #) but just for grins for howevermany gear teeth it actually has, what is degree spread two teeth?

If it is 16 teeth, it would be 360/16, right?

As I recall mine is set to point almost directly at 5 o'clock with the engine at TDC, which I think was the instructions that came with the rebuilt Dizzy. Mine seems to run fine and my gas mileage inspite of a TC no, or poor lock up problem has been running from 14 to 20 mpg (city/freeway). It also passed Texas severest Emissions tests recently at about 5% of the allowed limits, at 254,000 miles, so I think mine is set properly, optimized, but evertime I get into one of these dizzy indexing threads I begin to wonder.

Ecomike said:

Oldman,

Regarding the 15 degrees BTDC on the compression stroke, as I recall there just something like 16 gear teeth on the dizzy (I forget the exact #) but just for grins for howevermany gear teeth it actually has, what is degree spread two teeth?

If it is 16 teeth, it would be 360/16, right?

As I recall mine is set to point almost directly at 5 o'clock with the engine at TDC, which I think was the instructions that came with the rebuilt Dizzy. Mine seems to run fine and my gas mileage inspite of a TC no, or poor lock up problem has been running from 14 to 20 mpg (city/freeway). It also passed Texas severest Emissions tests recently at about 5% of the allowed limits, at 254,000 miles, so I think mine is set properly, optimized, but evertime I get into one of these dizzy indexing threads I begin to wonder.

Click to expand...

I can only go on personal experience here, but when I was fussing with my 87, there was only one position that worked well. A single tooth too far advanced would run fine, but started very hard, acting as if hydrolocked. A tooth retarded would start and idle beautifully but couldn't come off idle without stalling and spitting. So my guess is that if yours starts and runs well you have it right. In any case, since it's not that hard to do, you could always try moving it a tooth each way. Just make sure you mark the exact location of the rotor now so you can put it back reliably.

Plugged up Exhaust, cat ?
Fuel Pump ?
pete