I have been having a hell of a time with my truck. It was running rich so I changed the O2 sensor and it still smelled like it was rich so I took it in to be looked at. The mechanic adjusted the timing to specs (I think) and now it idles really low (about 600 rpms), It hesitates sometimes, and it still smells like its running rich. The truck just overall feels like the power isn't up to par. Any ideas on what I should check out?

Thanks

Check the TPS:
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Make sure the base timing changes when the timing/diagnostic jumper is installed. If not and the mechanic set your timing to 5 BTDC, your engine is about 7 degrees retarded on timing.

And make sure the vacuum line is attached to the fuel pressure regulator and that the Vacuum Switching Valve in between the intake and the FPR is working and connected properly. If not, consider bypassing it:
- http://www.4crawler.com/4x4/CheapTricks/22RE_Engine_Pix/8.html

please pm me if you find the problem. I dropped a new motor in and ive had the same problem since i have done it. Ive played with the timing, idle. but i don't understand the linky to the tps???? <img src="/forums/images/graemlins/confused.gif" alt="" /> i know electronics but not this.... please keep me informed

The TPS is just a variable resistor (potentiometer). It does two basic things, one is to tell the ECU that the throttle is closed (at idle) and off-idle, how far open the throttle plate is. It must be adjusted right to detect the idle position. If not adjusted right, the engine will not idle properly and you can't really set the timing properly.

He he, I'm having just about the same problem. Fairly new TPS, junkyard distributor, and I checked my timing before goin' on a wheelin' trip, and lo and behold, with the connector jumped, I have 35 degrees advance! WTF! Thought maybe I installed the distributor wrong the last time, it was fine. TPS may be the culprit though as I couldn't get two of the readings to jive, don't recall the exact names of the pins on the TPS... 2nd from top and the bottom pin yielded no continuity, where it should've had less than 2.3K Ohms...

Hmmm... I did gently wash the motor recently, but was careful to avoid the TPS - maybe some correlation?

The less the 2.3K ohms test is for the IDLe setting, without that and the ECU does not know that the engine is at idle, so you can't properly set the time, idle won't be smooth or steady, etc.

I've noticed its hard to start and I have to give it gas to fire up. Then while its cold and I get to that first stop sign it drops to 500rpms and when it gets warm it idles great. but throughout all driving it runs sluggish and then at like 3000rpms it just throws me back in my seat. I just want it to be constant.... im thinking dirty connectors on the injectors or maybe somewhere else.

Might give the fuel pump test jumper a shot for the hard start problem. And test the TPS and AFM to make sure they don't have any resistance dropouts over the closed to open range.

another thing to cheak out is your cold start injector along with your temp sensor. if the ecu thinks that the engine is not as warm as it is it will richen the fuel trim and possibly even not turn off the cold start injector.

i just went through my AFM and had to fix a little glitch that i noticed. the bar that pushes the contacts apart for the fuel pump was not pushing them apart, so any time key was in the ON position the fuel pump was pumping fuel.
another thing that i had to tinker with is the contact surface for the potentiometer. i had to take some contact cleaner put it on a q-tip and clean off the contact point. also you have to use a pencil eraser along with the contact cleaner, trust me on this one its a shop trick. be very care full not the get that contact cleaner on any other parts as it will corrode plastic parts and the sort.

i am having an issue with my motor missing and stunbling on its face right off of idle. i have gotten it down to only being until 1500 rpm~ish, but more messurable of hitting the throttle right off idle and it will studder, miss and than revs like the performance motor she really is. my power is really stong it is just the miss off the bottom end that i cant quite get rid of.

i have cheacked TPS,AFM,O2 sensor,spark, fuel injectors(one note here is that it seemed that the injectors were fireing really fast for being at idle, i have ran through all my performance upgrades and they should all be non conflicting(another note is that i have a stage 3 comp cam ; .445 valve lift, 110 lobe off set, 230 duration; and the factory manifold, down pipe, and a blown out flowmaster. i have a 4-2-1 header, 2.5" pipe and a brand new magna flow, would putting that full exhaust on there help get rid off that studder and (well to high performance engine builder) a sluggish rev, like its over cam'ed and needs a bit more flow?

by the way the exhaust manifold still gets red hot, but not as bright and only after extended driving, this leads me to think a lean conditon and i have heard about the AFM tweak to make it run richer or leaner but i have heard to both do it and also to not even think about it. a buddy of mine did that on his truck and he said it didn't give him alot of power increase, but im not after a power thing, just smooth runability.

thanks
nick

is the temp sensor the thermostat? or something else? bc that would make sense. but the injectors are new, cheap but new...