rcbigblock

OK all you Mr. GOODwrench guys, here's one for you.......I recently overhauled the 5.7 liter gas efi power plant in my wifes 90 full size Blazer and I opted for a set of Headman Headers insted of the C.I. exhaust manifolds but other than that everything is EXACTLY as it was before the re-build now to the Question ever since the overhaul (by the way it runs GREAT) when you pull on to the highway and place the Tranny in OD and it shifts up through the gears as before now when it shifts into OD the "Service Engine Soon" light comes on in the dash??????now all the fluid levels are correct I have great Oil pressure, normal operating temp., and Tranny is full and seems to be operating just fine.....my Question is why does this do this....the only thing that is not as it was as before is the O2 sensor the Headers did not come with a place to screw the sensor into them so it is hooked up just not inserted into the Header.....could this be the malfunction and the computer is reading this as a error or fault and therefore trips the light in the dash ???? I am very old school here and still learning about all the computer tech stuff I have missed out on these past few years so any advice would be greatly appreciated.
Thanks ,
R.C.

John86

well the o2 sensor needs to be screwed into the exhuast so ur computer can get an accurate reading of the air/fuel mixture. your o2 will be getting out of spec readings turning to ses light on. do u have a way of scanning it to get a dtc?

golfer

The O2 sensor has to be in the exhaust stream ... I'm surprised it runs " GREAT ".
If you have a cross over pipe between the left and right exhaust mount it there. Any muffler shop can weld an O2bungin place.

John86

u can also buy o2s simulators if u don't want to drill into ur headers or exhaust pipes.

jojo

I'm working on a 94 chevy silverado 3500 HDwith a 6.5L diesel turbo engine. It is a cab and chassis with a custombuilt hydraulic flatbed. The engine stalls intermittently and registers code 35 which is an injection pulse width error. Scanner reads 1.8ms pulse width at abnormally high idle speed of 1100rpm. While i was doing a pin voltage testing, i discovered that pin A6 of the ECM was hotwired to ignition. Schematic diagram reveals that there should be no connection to A6.Tried to disconnect the wire and rpm dropped to around 700 rpm with a pulse width reading of 1.77ms but engine still stalls while accelerating and after the service engine soon light turns on registering same code 35. Is the the connection of A6 to ignition an acceptable or authorized modification apparently to raise the rpm to boost the pressure of the hydraulic pump of the flatbed? Has it caused a potential damage to the ECM causing the engine to stall intermittently?Likewise, is there any idea why theclutch does not engage after replacing the clutch kit with a new dual mass flywheel?Are there other possibilitiescausing the engine to stall intermittently?Any advise or help is greatly appreciated.