Tbi rough idle

[k5Thumper]

hello, got an 88 k5 TBI 350 that has an occasional miss, especially at idle. It’ll stall out when I get home from work and put it in reverse to back into the driveway. Has new o2 sensor, fuel pump, cleaned and rebuilt TBI (same injectors) and new tps sensor. Has newer plugs/wires/dist and vac lines look solid. Is there something obvious I’m missing? Thanks

 

[wheels87k5]

Check the EGR solenoid and EGR valve.

https://ck5.com/forums/threads/what-are-symptoms-of-a-bad-egr-valve.273367/

 

[k5Thumper]

Will do! thanks for the link

 

[jeff in co]

And Idle Air Control valve too.

 

[k5Thumper]

can these act up without an active CEL?

 

[wheels87k5]

Yes.....you can have a bad EGR valve or solenoid and depending on your driving it may not cause a CEL.

You can also have a good EGR valve and solenoid and it will set a CEL. This happens if you do some upgrades to the TBI system and don't have the ECM chip flashed to meet the new demands.

Not sure about the IAC not setting a CEL.

 

[k5Thumper]

Cool. Gonna check the egr for excess carbon build up and if it looks bad throw in a new one Saturday or Sunday, I’m guessing this is a part I want to keep oem. Appreciate it fellas

 

[paratrooper307]

Even if the lines look good, any time idle or stumbling issues pop up, always check for a vacuum leak, especially if there's been recent TBI/manifold work. Fuel injected engines will try to compensate for the leak which can make them more intermittent and harder to notice.