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Tbi gurus need help

dheavychevy38

dheavychevy38

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Algonquin,illinois
Ok i have a 89 k5 with a stock 350 tbi only thing done to it is headers.
The problem i have is it keeps eating O2 sensors and is running rich.I put the scanner on it ran it like they do for emissions and when i come down from 2500 rpm to idle the truck stays in a rich mode and won't go lean until i hit the gas again?
One thing that cofuses me is that the o2 reads rich in that situation but all the other sensors read lean the only one that is out of spec is the map spec is
at 9 hg 1.1 and at 12hg 1.7 mine reads 10 hg 1.29 to 1.40 need ideas i am going to order a new cap,rotor,wires and coil. I did a tune up about 6 months ago but that was with napa stuff. Thanks
 
where is the o2 sensor? buy the head or at the colector? if at colector then you need to switch to a heated one . the nonheated wont get warm down there to work correctly . i need it for my tbi swap. mine is at the y pipe at bottem of exaust . no fitting on manifolds
 
buy the way you cant put the sensor in just one tube off the head , it needs an average from the 4 ports thats y its at the back of the manifold from factory.
 
The O2 is right where the 4 pipes dump into the collecter i moved it from the reducer it's about 80 to 110 degree difference in that little area. If you hooked up the heated one how would that work with the 3 wires? Wouldn't it burn up if you just wired it to a switch?
 
there was a thred on here not to long ago and if not there call a tbi specilty house . howell-efi.com did my unit thay have o2 kits.
 
What temp thermostat you got? Have you got any heat? You got a scanner...What is it showing for temp. Put a 195 stat back in. that FI was designed to use that temp.


Gas usualy doesnt ruin the sensors....OIL ruins the sensors. Is it using oil? Pull the plugs and see if they have oil deposits. Also make sure there are no mainifold leaks. Manifold leak will draw air in and throw off the samples. Bad manifold gasket on my Yota was causing 1.5 mpg drop. Actually ANY vacume leak can throw stuff off. I would check the gaskets at the TBI. Leak there could throw off the MAP sensor. ;)
 
The heat is great just put a new 195 t-stat along with a heater core in.Tbi gasket new and no it doesn't use any oil this thing runs good just not good enough for the state. i have already ran it on the shop scanner the only code it throws is a vss but it say to disregard it if the vehicle is in park or neutral
 
stuped ? do you have a chip or programer in it ? that will somtimes thro off the state crap.. i had a jet chip and it said to put stock back in any time there was a sensor problem that wasnt easly fixed and recheck it .
 
Nope i have never monkeyed with the ecm the only thing i changed was to headers and the postion of the o2 sensor. cause before it wasn't going into closed loop with the sensor in the reducer so i moved it foreward in the header.This is the 2nd o2 in less than 6 months that has taken a dump and they are factory acdelcos.
 
dheavychevy38 said:
The heat is great just put a new 195 t-stat along with a heater core in.Tbi gasket new and no it doesn't use any oil this thing runs good just not good enough for the state. i have already ran it on the shop scanner the only code it throws is a vss but it say to disregard it if the vehicle is in park or neutral
Click to expand...


Check the VSS! If it does not get a VSS code as its read "open" like it cant see the VSS it may go into limp. The VSS lets the ECM know when it has stopped and it goes to a lean condition by design. Its ok to be lean at idle because it not a load condtion.
 
VSS on 89 should still be on the back of the speedo. it uses a optical sensor throug ha hole in the back of the housing. Its on its own plug as I recall.


If the cruise works then its probably ok. uses the same sensor.
 
He's got a scanner, watch the vehicle speed through it to confirm VSS.

Have you looked at your TPS values as you go through the throttle SLOWLY?
 
Cruise isn't hooked up. Going off of what the book said that came with the scanner if the vss code is thrown when in park or neutral to not worry about it. It works fine when you drive it as soon as you start to drive and it sees it the check engine light goes off.
 
Tps when at idle is .64v haven't checked it at wot but i know it changes it's values smoothly as you increase and decrease the throttle pedal.
 
hay check the temp on the scanner compared to the gage its a diffrent sender and could be bad and sending wrong info to computer.
 
Gauge read the same as the scanner when the truck is running. Ok the tps
reads
Idle .62v
just off idle 1.37v
rate increases then about half throttle .00 v
.00v up to 1.00v then it goes to wot 4.40 i guess it isn't reading to good:doah:
This was with key on engine off.
 
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