surge/miss

[scotto0609]

I posted this in another section and they referred me here so here goes.Just picked up a 91 cc dually bb 4wd and it seems to run great buuuttttt at steady cruise after @60 mph it starts the surge/miss problem.The truck just recieved new plugs wires cap rotor and fuel/air filter. The silencer tube is broken where it enters the air filter assembly,and there seems to be no vacuum leaks. Any ideas would really help. Thanx Scott
On a kinda related I have read about downloading codes,can I do this on my truck? thanx again

 

[eagle mark]

Yes you can get codes from it. Look for directions in the sticky on top of this forum.

Your surge miss, with the information you describe sounds like an EGR issue. Since it's running good all the time and you notice this at cruise that is when the EGR would be opened. You could check by disconecting the vacuum line to EGR and give a test drive. HTH!

 

[scotto0609]

Took a drive today with no egr and there was no change. than i figured out how to download codes and all i got was 12's,except one time I thought I got a 13. So should I try a new O2 sensor?

 

[Jessie James]

Do you have headers, if so then you may need a heated O2 sensor. Otherwise, if you are stock, then the O2 sensor may be to blame.

 

[eagle mark]

Took a drive today with no egr and there was no change. than i figured out how to download codes and all i got was 12's,except one time I thought I got a 13. So should I try a new O2 sensor?

12 is good, that means the test is working. That said and your first post problems I would next check fuel pressure. Should be close to 13 PSI and stay steady if you stab the throttle and rev it up!

Have you checked for vacuum leaks? BB Chevy are notoriuos for vacuum leaks around the TBI because there bore is so big there's not much gasket. Replacing it would not be that expensive or time consuming. HTH!

Do you have headers, if so then you may need a heated O2 sensor. Otherwise, if you are stock, then the O2 sensor may be to blame.

Like Jesse james said may be an O2, they do wear out and can become useless if you have recently used some kind of silicone sealer that is not sensor safe. I don't like to replace parts that don't need it, would rather diagnose the problem. But sometimes DIY guys just don't have the equiptment needed to diagnose. That said O2 sensors are fairly cheap in the $25 to $35 range and it won't hurt to replace it.

 

[TexasSilhouette]

Doubt its an O2 sensor, it does not sound at all like an O2 issue. Disconnect it and see, you will likely set an O2 code but the engine will run in open loop and is otherwise harmless.
Edit:See if you can duplicate the symptom by repeating the throttle movement or see if it is associated with a throttle movement. A flat (dead) spot in a TPS will make a "hiccup" per se'. If this appears to be a possibility, a sweep test of the TPS should catch it. We did a recall on a bazillion TPSs years ago for a hiccup symptom. I did not think they would ever stop comming.

 

[eagle mark]

Your welder really fuel injected?

 

[TexasSilhouette]

Your welder really fuel injected?

Yup!

25HP Kholer W/Delphi EFI. 12,000 watts of aux power.

 

[scotto0609]

Should have just left it alone. When out to move it and the truck ran super rich and would not idle for @ 1-2 minutes,when it did idle on its own the check engine light came on. Cleared the codes,started it,same thing. Shut it off,pulled the codes and this time I got 12,13,14,. SSooooooo I guess I need to look at the o2 sensor AND the water temp sensor now. I was so excited to get this truck and be able to kinda learn modern stuff,......................be careful what you wish for..........

 

[4xcrazy]

I'd still check the fuel pressure, when my pump went out, or was going out, it was throwing all kinds of codes for several different sensors. It confuses one sensor, so that one reacts, but in turn that adjustment affects another sensor, and just creates a chain reaction.

I replaced several things until I finally realized it was low fuel pressure causing all my headaches. This was in my early days of owning a TBI motor too..