Hello all, Did a tune up, plugs,coil, wires, cap, rotor, fuel filter. ran great, went on a road trip. on return had rough idle, good at speed, checked codes old fashioned way. replaced EGR, MAP, idle control, ECM and injectors. no help! still driving daily. thought intake leak, temp went up one day, checked raditor level - empty. head gasket! fixed top end. still has rough idle, runs fantastic at speed, once moving pickup is great. compression is equal in all cylinders, not a good spray pattern from injectors (TBI) on idle, good cone of gas while increasing idle, have not checked fuel pressure, trying to chase down a gauge. fuel pump? help please

 

The temp sensor for the ECU could be reading wrong as it controls the fuel mixture. This is the sender that is located by the water inlet at the intake maniforld. I would also consider the O2 sensor. Once the engine is warm and in closed loop operation then the O2 Sensor comes into play for fuel mixture. Hope this helps. You should also check for vacuum leaks. For fuel pressure you need 9-11 PSI. 11 PSI is optimal.

 

I better get a new connector for the sending unit. a wire broke at the connection, I used solder to reconnect but may not be a solid contact. I forgot I did replace the O2 from a code.

 

Ordered the sensor today (I live in a black hole-Indio, CA) Let you know when I get it

 

I replaced the sensor, the rich condition is gone and have a good cone at the injectors at all times but it is running worse. Idle is still rough and will cause the engine to die while in gear, in neutral or park it will idle really rough for 15 seconds the pick up and be smooth for 15 this continues back anf forth. it will drive smooth at times others will be hard to get moving sputtering. have not tested fuel pressure but that does not seam to be a problem. any ideas????

 

Fuel pressure or vacuum leak would be my suspects. You can spray gumout at the base of the tbi. Cap off each of the vacuum ports to see if you have any improvements. Cap off the EGR vacuum line to make sure that the EGR is not being opened by a faulty EGR solonoid.

 

Thank you Mr. VLS for your help and input!
I had already used gumout on all areas searching for a leak.
I ended up taking the car to a shop of a friends buddy, we went over the vauuum system again, he was busy, suggested removing the EGR and making a blockoff plate and reinstalling. he thought the engine was running rich due to the computer but he also thought the exhaust smell was quite strong, ie internal vacuum leak. it worked, faulty EGR, runs perfect now. still need to get a new EGR (today) He did not charge for his 30 min of time, but I will stop by and drop him some $ for his time.

May God smile on you Mr. VLS

Dean

 

Glad to help, the only reason I did not sugest the EGR itself as you said you replaced it. I am the original owner of my 89 Jimmy so I have been through many of the same symptoms at different times during it's lifetime. If you can afford it get an AC Delco or GM EGR. They are much better built and will perform for a very long time. In over 420K miles I have had 3 EGRs, Orignal and 2 replacements.

 

Well hhere we are! Installed the new EGR ran great till it was at temp, would run good for 2 or 3 more miles, at a light for more than a minute it would idle rough and surge some, on take off it boggs and sputters till you get to speed, next light if its short it goes fine and so on. acts like temp sensor, installed a new one, no luck. I have an electric fan it was set to the 190 range, thought the gauge may be off so I upped it to 200 no change. and of course no codes. I read another post on sputter, fixed by replacing motor mounts?? could this be vibration messin with the knock sensor. how do I tell if thier bad? tired of throwing money around. Ideas???

 

When my motor mounts went bad the motor would shift so much that the fan sliced the upper radiator hose.