1998 Bucking Rodeo

[StevenZ]

I have a 1998 Rodeo (2WD) with a V6 and manual transmission (116K miles). I've spent a lot of time fixing issues that are inherent with this year/model. I'm down to one last issue and it has me perplexed. Seems as though whenever the temperature drops outside into the 30s and below, I get a hesitation when accelerating - a flat spot. The vehicle idles find and runs fine once it's just off idle, but if I'm at a stop sign and start to pull away, light accelerate causes the rodeo to buck - hesitate. If I push the accelerating a bit further, it seems there is a bit of a lag, but then it snaps out of it and runs fine. Come to the next stop sign and similar problems. It doesn't seem to matter if the vehicle is cold or warmed up. I've been through/cleaned the EGR, IAC, MAF systems. I've replaced the fuel filter and checked all wiring for loose/broken connections. Still no success. Seems like it's related to the cold air and fuel mixture, but not sure how that can be checked/adjusted. Once the weather warms up, all is fine (yes, I wish I could move to a warmer climate). Any help on this issue would be greatly appreciated. Want to finally 'tame' my bucking Rodeo.

[SleepyHead98]

you have to have a Check engine light on. What does it say. Im thinking maybe plugs and wires? Possibly coil packs? Only other thought is maybe fuel pressure not right? or preassure regulator not right?

[StevenZ]

Thanks for the reply. No CEL and haven't replaced the wires/plugs. Not sure on the fuel side. All works fine in warm weather; just occurs when colder weather sets in. Would think plugs/wires might be problematic regardless of weather. Fuel pressure may be something to look at, but it runs fine at higher RPMs making me thing that that's when there might be a greater need for fuel - making the condition worse.

[SleepyHead98]

It happens at idle at every stop, so something if def wrong. Just a matter of figuring out exactly what it is. Hard to believe there is not a CEL. Maybe TPS (throttle position sensor), but it should have thrown a code.

[StevenZ]

Thanks for the response, but no CEL.

[SleepyHead98]

Might have to get a 5 dollar multimeter to check the output volts of each sensor to ensure it is working correctly.

[SleepyHead98]

Put a multimeter on the output volts of the MAF sensor. MAF volt outputs should change/correlate exactly with the revs of the engine. If it drops off or is random, its a bad maf.

[amigo-2k]

I see you are in Madison ... so am I ...

it could be caused by a leaking intake manifold gasket (super common, I've had mine replace 3x during the life of the truck).

[StevenZ]

Thanks amigo-2k for the reply and I'll take another look at the IMGs. They have been replaced once, but if you've had to replace yours a couple times, it has me wondering. Being a Madisonite; I'm sure you can appreciate I've got a couple other priorities the next couple of days - shoveling snow..... Ugh!

Later,

[SleepyHead98]

Post back with solution!

[StevenZ]

So finally had a chance to work on the Rodeo. Pulled the throttle body and gave it a good cleaning. Checked the EGR tube - all's good. Cleaned the MAF again and reassembled. Drove about 40 miles today and all seems to be running fine. I'm thinking the bucking was related to build up in the throttle body. Will continue to monitor and post if problem re-occurs.

Thank you all for replying to my post!

[StevenZ]

Well, off-idle hesitation reappeared. Decided to replace MAF. After install, all appears to be working fine. Hope this finally cures the problem.

[Thomas Sams]

dude i think if the engine light status is good then problem in plug or wire because i was also same problem last year after lot of struggle i find that wire is damaged that why engine is not working properly...