m4ttj00

Hey guys,
I recently decided to replace my TPS and upgrade my injectors for an mpg and possible performance boost. I did a lot of reading on this and other forums before making the decision.

First, a little background on the truck. I bought the truck with a blown head-gasket. I had a rebuilt engine installed by a guy in Vancouver, WA. He did a great job, and I've been running the engine for well over a year now without any issues. So, I get about 17 mpg highway, and 10 city. I'm also running a 2" lift on bgf ko2 31's.

So I ordered a new OE Toyota TPS(matched part number) and a set of flamethrower injectors. Everything installed without issue, but I'm having trouble getting the truck to accelerate smoothly following either the factory throttle body calibration or the guide on LCE Performance. The truck starts up and runs great from cold, but when it warms up the acceleration from stop has some hesitation, plus you can hear the injectors firing erratically. Again, I've read through other threads on the subject and tried to follow every possible piece of advice.

My adjustment procedure is as follows: First, I warm the truck up. I then loosen the TPS bolts (I've upgraded to allen) and hook my multimeter leads to alligator clips on E2 (top pin) and IDL (3rd pin down). I secure the idle opener with a zip tie as not to interfere with the calibration. I then remove the dashpot so I can access the idle stop screw. I adjust the screw so it makes contact with the plate +.25 of a turn. I Then insert a .50mm shim between the the throttle stop and the plate and rotate the TPS clockwise until the point where I lose continuity. I back off until continuity is restored and secure the TPS bolts. I then remove the .50mm shim and insert a .80mm and ensure that there is now no continuity between E2 and IDL. I've also tried some variants of this calibration where the shims are .77mm and .85mm. With the 5 adjustments I've made, I always get some hesitation and non-uniform injector firing. Now, when I unplug the TPS, the truck goes back into the state before the TPS/injector upgrade making me believe it's been running uncalibrated since I had the new engine installed. I get noticeably more power with the TPS connected, but again there is some hesitation at low RPMs.

Tonight, I tried a different calibration technique I read about. I warmed up the truck, loosened the tps bolts and then moved the tps clockwise until I heard the idle speed up. I then moved the tps counterclockwise until the idle kicked back down and tightened the bolts. Same issue, irratic ticking of the injectors. I then loosened the tps and moved clockwise to find the point where the idle kicks up, and back counterclockwise where it kicked down, but then a few CM more. Now it accelerates smoothly, but the OHM calibration is out of spec.

Any help/advice would be appreciated.

warpigg

What makes those injectors different/better? I'm assuming higher flow rate, how much higher? Did you adjust your airflow meter to compensate for the new injectors? Are the injectors the same impedance as the old ones? Did you try hooking up your old tps or injectors to see if it runs normal?

m4ttj00

I came across some posts on the subject. Either this company does good work or their marketing works. It could very well be that these injectors simply work better because my previous set had a bilziilon miles on 'em. The new ones sound more uniform and produce a different exhaust note.

m4ttj00

I was wrong about it accelerating smoothly with the tps out of spec; it simply moved the hesitation to a different point in acceleration. I think the tps was initially adjusted where it was kicking in at a point where I only noticed the hesitation at high rpms. I also replaced the spark plugs after reading a thread where it solved someones stumbling issues; this did not solve the issue for me.

I stumbled across another thread where the egr actuator was the issue. I pulled the vacuum line of actuator and plugged it. Well, so far so good! Acceleration is now smooth.

I'll keep this thread updated as I learn more.

m4ttj00

Day two with a plugged egr vacuum actuator line. I did readjust the the tps so it's in fsm spec last night.

The truck has more power than ever. This leads me to believe that the old tps was defective all along and I've been running with retarded timing this whole time. The new injectors are quieter and sound more uniform. I don't have a fair frame of reference to compare them to, though.

Does anyone have an opinion on blocking the erg vacuum line? The truck has one more emmisions check (next year) before it's 25 years old and exempt. Part of me wants to just rock the current setup, but I'm afraid of toasting the cat or clogging something.

warpigg

You can take your egr off and run block off plates till you have emissions testing and then throw it back on. Or run block off plates till you get your egr unplugged and cleaned then when you go to throw it back on clean the EGR runner in the intake plenum. I'm not familiar with those v6's so idk where the EGR mounts or where the runner is in the plenum.

warpigg

You shouldn't cause any harm to your cat and the only thing that's already clogged is your egr and or it's ports by the sounds of it