Hooked up my TPI Monte up using a scantool a friend had and checked the vitals.

Also used a vac gauge and fuel pressure gauge(vac reading of 15 and FP 42psi).

The two problems we found was the coolant temperature reading was 203 degrees...the car was warmed before testing but it was wouldnt go into closed loop. My temperature gauge that takes the temp at the water pump was running at 180 for awhile, which is the normal running temp.

What are possible causes of not going into closed loop?

The car has no current codes but has gotten 43 before as well as the EGR code, but they are very infrequent/rare occassions. Nothing lately.

Car runs *ok* but the power and mileage dont seem to be quite where they should be. If it indeed was stuck in open loop all the time it might be the reason I guess. Looking for answers to this mystery ...TIA!

 

sometimes even though there is no code for it, if the o2 doesn't heat up and start switching, it will not go into closed loop. did you happen to notice if the o2 was switching or staying at one spot?

 

Wouldnt the O2 set a code if it wasnt letting the car get into closed loop? Just curious.

What else could be possible causes?

The car has headers and the O2 is about 10" lower than the stock location, if that makes a difference. Might need a heated O2.

 

I have the same problem with my L98. It was in the truck when I bought it and most of the smog is still there but not functional. The egr has a plate in its place and I moved the o2 from the lower position back to the header. I had to cut and reweld the bung though because of frame clearance. I have looked and looked and found nothing to fix my problem. I know my truck is heavier than most cars and but I only get about 11 mpg on the highway. TERRIBLE! If find anything out let me know.

 

No. It doesn't set a code when you start the engine cold, so if it never starts swinging high/low the ECM is just going to ignore it.

 

Morley is correct. No code for that. I think you may need a heated o2 sensor. As far as the cts temp compared to your guage temp, that's 100% normal.

 

I had the same problem when I installed TPIS long tube headers on my Vette.

Using Diacom to show me what was going on, the system would drop out of closed loop at idle. Problem is the 02 sensor is now too far away from the exhaust port to maintain the required 600F needed.

I bought and installed a heated sensor and that cured the problem.

Hope this helps.

Jake

Jake