1999 Rodeo, surging idle

[jikchung]

No instrument codes generated. Shop sprayed for IMG leak, hooked up the computer and all reads fine but still surging. Unhooked the power steering sensor with no change. I'm thinking TPS or IMG. Thinking of changing both, opinions?

Thanks,
Dwight

[amigo-2k]

The butterfly in the throttle body could be carboned up.

The 1st my IMG went I had no codes, and the RPM would jump up and down only like 50-100 RPM while sitting at a light. I took it in and then said the IMG was cracked.

typically if it is surging and you all other things are in order the IMG is cracked....

[jikchung]

Thanks Ryan, they are going to change the IMG (at my insistence), we'll see. I also suggested cleaning the butterfly.

Dwight

[jikchung]

New IMG, new IAC, new TPS, cleaned Throttle Body, still surging... Any other ideas?

[amigo-2k]

Weak electrical system? dieing battery? poor ground? dieing alt?

[jikchung]

Going to check those out this week (been out of town since my last post).

Talked to an Isuzu tech who also suggested it could be a stretched timing belt (I'm the second owner, 130k, guessing that the previous owner did not change the belt at 90K). Any thoughts on this?

Good news is that the IMG they installed is a newer design with solid metal around all the openings rather than the simple sandwich design of the previous ones.

[FL 3.2L]

Ask if they used an OEM TPS. I have not had luck with aftermarket when this problem creeps up. When the TPS is the issue, the scanner shows that the TPS is reading high when surging. There is no code, but the live data for the TPS is altered.

[jikchung]

Scanner data showed normal. Was getting ready to have the timimg belt changed when the surging stopped. Has been running normally for the past week & a half. Weird.

Thanks for all the replies.

[jikchung]

Ok, this has now become an intermittent problem, maybe about 5% of the time, otherwise runs normally. Any other thoughts on causes that would not throw a code?

[austinrodeo]

@jikchung Did you ever resolve this problem?

I just bought a 2002 and am now experiencing same problem.

Throttle varies at stop light when transmission is in drive, and it also 'pulses' when driving around 20 - 25 mph (the engine fluctuates between 1300 & 1700 RPM, causing the vehicle to surge.)

Also when stopping with the vehicle still in drive, foot on break, no contact with accelerator, the vehicle seems to strain forward, the idle increases, then the vehicle lunges and stops. The sensation is as if the transmission does not shift in to a neutral state until the car surges forward then the forward force ceases.

This does not happen as much when the car is hot.

I just cleaned the throttle intake.

Any suggestions on other areas needing attention? EGR valve? etc?
Thanks.

[joshua2836]

I have been having the almost same issue. p0133 b1s1 but its like surging under light throttle but when you get on it clears up. #3 misfire intermit. then now misfire. surge really bad under light acc. Seems like it might be a spot on TPS. Sitting at idle runs great. Its acting like fuel starvation but change fuel filter and pum is pumping good. Any ideas?

[amigo-2k]

you could move the coil (#3) to another location to see if the coil is weak.

The common problem is the intake manifold gasket going bad (It seems like they last about 50k).

[joshua2836]

Thx bro tryed the coils all cyl hitting today. Think im gonna go the intake gasket way. Thx for the input