hows it going i got a 88 na and it has a rb header on it but no bung for the 02 sensor? acutally the car never had a o2 sensor in it since i bought it. lol one of those things i over looked . the car seems to be running fine exept after i have been driving for about 30 or more minutes and the car wont go past 4k...would this problem be occuring because of the missing o2 sensor and the car being stuck in closed looop?

 

No. A car with no 02 sensor will be unable to go into closed loop (02 sensor input used by the ECU). Open loop is the operating mode under all non-cruising conditions, and there is no reason this would prevent the engine from passing 4000 RPM. I'd start by pulling codes: http://www.teamfc3s.org/info/article...odes/main.html. Your description suggests it may be temperature related, so the water temperature sensor on the back of the water pump housing may be bad. The ECU uses it for temperature based fuel corrections, and if it fails, a default value will be used. This can cause some odd behavior.

 

sweet ill check that site and the sensor out but i should probly put a 02 sensor in the car right?

 

Running with out a o2 might make you a little richer but it's no big deal.

 

i figured richer and probly bad gas mileage like 160 to a tank lol

 

Not going past four grand MIGHT be one of the secondary elect plugs is not making contact with the secondary fuel injector. Or one of the sockets in one of the secondary elect plugs has a socket pushed back in the plug not making contact.

The above would be true IF you can gently drive the car over four grand using light pedal input i.e.no LOAD on the engine. IF that is the case, then what I wrote above is a good possibility. 02 won't cause this problem.

 

update:ok i have checked all the plugs cleaned all connections and checked the thermo sensor for the ecu..the plug was slightly off so i cleaned and reconnected and then took it for a cruise..after about 2hrs of driving the problem didnt happen at all i had perfect throttle response and the car ran perfect! im guessing like rotaryrocket said that thermo sensor might have been the culprit...im still looking for that o2 sensor connector. It should be behind the intake manifold if im correct but its missing

 

I think i found it . it looks like a o2 sensor wire cause it has some sheilding on the wire but i cant figure out why it is grounded? lol can anyone confirm this?

 

anyone?

 

The secondary fuel injectors kick in at 3800 rpm. Usually the injectors themselves are fine but they often have a bad signal. The ECU ground is the most common culprit, but then again it also usually hesitates instead of failing completely. There are other causes too. See: www.aaroncake.net for more information. A forum search on "won't go over 4000 rpm" or something similar may be even more helpful, since secondary injector problems are very common.

The O2 sensor is good for about 2 mpg and only on the freeway. It also reduces emissions. It serves no other purpose. You should get one, but no need to hurry.

 

i got the grounds all covered,i ont have the hesitation. it looks like the o2 sensor wire is grounded if this is the wire. thats all i want to know. thanks anyway though

 

anyone? i am going to work on it again tomorrow. if this isnt the wire then i wont weld the bung to the header for the o2

 

The wire will be Grey and will be part of the emission harness which also houses the Black ground that is found on top of the UIM.