surging at low rpm

[blacksvt99]

Has anyone experienced surging at low rpm in there vehicle? My car has been doing this for about 3 days. No check engine light present nor any codes pending. I cleaned the maf sensor and it still seems to do the same. I replaced the fuel fitler about a year ago.

 

[01bluesnake]

what are you considering low rpms, under 700? may have a slight vacuum leak, check your fuel trims and o2's if you have access to a good scan tool.

 

[Black*Death]

Iac?????

 

[blacksvt99]

The surging is felt only when driving between 1000 to about 2500 rpms. I tryed looking at the o2's,fuel trim,load,and maf values but the scan was useless. I am gonna go to my cousins work and hook up his solus scanner.

 

[01bluesnake]

if you can use the solus, datalog your tp, ect, iat, o2's, fuel trims, load, maf, baro, timing advance. do a constant throttle accel trying to move the throttle as little as possible to keep a steady log and see if anything looks out of wack as soon as it starts to surge when doing play back. i've seen some TPS issues cause surge on a steady accel as well as bad o2's. also monitor your fuel injector pulse with for possible sticking injector with any obvious difference in bank 1 and 2 fuel trims. Remember that your long trim is your overall correction and your short is your current correction of which your o2's will control.

 

[blacksvt99]

Well went to my cousins shop and hooked up the solus and everything is normal. There is no abnormal values showing on the scan tool. We checked fuel pressure fuel pressure at 28psi. Also did a fuel pressure volume test it took about 56 seconds to fill up a quart with fuel.

 

[NukeGuard]

I had this same issue a few years ago. After changing the plugs, ensuring the COP's were well connected, changing the fuel filter, cleaning the MAF and running through a few tanks of known good fuel (no ethanol, no off brand gas) the problem went away. I still don't have a solid explanation of what caused it. You're not the only one, there are quite a few threads on instances like this.