Oxygen Sensor Location Question

[BillS]

My Fiero of course has the sensor in (more or less, as it is turboed) the stock location.

This question is in regard to another front engined sports car I have just finished building, using a 3.4 Camaro engine.

It wasn't possible to use the stock Camaro twin sensors in the exhaust manifolds (one of the first thing sI did was chuck them and modify some bored out Fiero tubular manifolds to suit). I was concerned with the fact that the sensor would now be aboput 2.5' downstream, so I fitted a heated sensor to get proper readings quicker.

I later talked to a guy who gets cars through our emissions testing and he said that a regular sensor installed way downstream withh still work, it will just take longer to heat up. Was I being worried about nothing - could I have used a stock sensor that far away from the engine?

This thing took a year and a half to finish, but very interesting to do. Pic at http://www.rhodo.citymax.com/i/non-rhodo/March07a.jpg and http://www.rhodo.citymax.com/i/non-rhodo/DIS2.jpg

I used a 94/95 engine but backdated to a 1990 or so OBD 1 ECM for ease of programming - much rather send the chip out than have to send the whole computer. It meant losing the SFI, but I kept the DIS, which frankly would make a nice conversion on the Fiero - it would save me having to rebuild my distributor every few years from the effects of the heat from the turbo. But since I am using the hole in the crankcase for my knock sensor already I'd have to figure out where to relocate it so I could install the crank position sensor in its place.

[Guest]

First pic link doesn't work.

You won't need to relocate the KS, because the CPS doesn't go there anyway.

You're best bet, when using a block that does not have provisions for the CPS is to build an external crank trigger, or if the one from the one from the store will work for you, then you can use that.

Back to your original question, yes the non-heated sensor would have worked, but there is nothing wrong with using the headted O2 sensor, I'll be converting mine when I put my engine back together again.

[BillS]

First pic link doesn't work.

You won't need to relocate the KS, because the CPS doesn't go there anyway.

Back to your original question, yes the non-heated sensor would have worked, but there is nothing wrong with using the headted O2 sensor, I'll be converting mine when I put my engine back together again.

I thought it did!

The CPS on the 3.4 engine is certainly in the same place as the KS I installed in the 2.8. Are you sure that the late (87-8 blocks didn't have the CPS bung drilled and tapped even if they weren't being used for the particular application?

The 3.4 has a CPS on the block (only one I am using) a CPS on the crank pulley and a Cam PS as well to run the SFI (which I removed and plugged - there seemed to be no after market cams available with the 'bump' to run the SFI system).

PS - fixed the link - the car doesn't LOOK anything like a GM - because it is an MG.

[Guest]

I thought it did!

The CPS on the 3.4 engine is certainly in the same place as the KS I installed in the 2.8. Are you sure that the late (87-8 blocks didn't have the CPS bung drilled and tapped even if they weren't being used for the particular application?

The 3.4 has a CPS on the block (only one I am using) a CPS on the crank pulley and a Cam PS as well to run the SFI (which I removed and plugged - there seemed to be no after market cams available with the 'bump' to run the SFI system).

PS - fixed the link - the car doesn't LOOK anything like a GM - because it is an MG.

Yes I can't be any more possitive that the RWD blocks (other than the 3.4) do not have the CPS boss, not even an undrilled/tapped bump. The KS gets threded into a blind hole is a place that is close proximity to where the CPS would be. Yes the 3.4 using a very similar sensor system and design to the FWD SFI engine, including the 24x crank sensor mounted behind the harminc balancer, and the cam position sensor that is used purely to run the SFI, for the home signal, and IIRC only at start up.

What model of MG is that? pretty sporty looking.

I haven't verifyied this, but I think that the cam I have in my engine has a bump that would trigger the cam position sensor, as it seemed to have a bump that looked to be about teh right position, but didn't look farther into it, since I'm running MPFI (batch fire).

[BillS]

Yes I can't be any more possitive that the RWD blocks (other than the 3.4) do not have the CPS boss, not even an undrilled/tapped bump. The KS gets threded into a blind hole is a place that is close proximity to where the CPS would be.

What model of MG is that? pretty sporty looking.

I haven't verifyied this, but I think that the cam I have in my engine has a bump that would trigger the cam position sensor, as it seemed to have a bump that looked to be about teh right position, but didn't look farther into it, since I'm running MPFI (batch fire).

It has been so long since I had to look at the KS in my Fiero that I can't recall if it is exactly the same as the 3.4 location but now I will have to remember to take a look. The Fiero was an 1988 transverse block of course, so maybe the tapped hole in that WAS meant for KS?

I called all the major cam companies and not one of them used the blank with the requisite bump for SFI. That was part of the reason I decided to lose the SFI; having to send in the entire PCM for reprogramming was the other reason.

The car is a 1957 MGA with a Fiberfab Jamaican body on it. Pics at http://www.rhodo.citymax.com/Jamaican.html

I did the usual things to bump the output on the 3.4 a bit - lots of intake work, larger throttle body, cam, modified exhaust. No idea where that takes one - somewhere between 180 and 200 I should think.

In any case, quite peppy in a car that weighs less than 2000 lbs.

Used a Camaro V8 T5 trans (better ratios) and a 3.9 diff, which adds to that peppiness while allowing for relaxed top gear cruising.

Fortunately the engine fired the first time I hit the start button, or I'd probably still be up to my ears in wiring and testing.