[FIXED] Long injector on time

I am a tech here in New Zealand and I have a car which is doing my head in. Symptoms are once the vehicle gets hot the injectors start having a open time of 11ms. O2 is fixed rich and responds to vacuum, ECT and airflow sensor appear to be operating correctly on the scope. Am I missing something.

The vehicle is a 95 Nissan Pulsar with a GA15 motor

Any ideas would be amazing.

What are your fuel trim values?
How well does it run?

Hmmmm, we didn't get the GA15 here in the States... I'm guessing the GA16 is pretty similar?

Like pole71 mentioned, aside from the rich condition, how does it run? I'm wondering about a possible stuck open EGR valve, if the GA15 is equipped with one.

Fuel pressure is probably a huge pain to check on this engine, so I'd probably stay with the airflow sensor. Any grams/second scan data reading we could use? Or, can you check what the sensor signal voltage is at idle? Was thinking about trying to find some known good values for comparison.

It runs ok then all of a sudden you get the injectors opening at 11sec. Of course once that happens it runs rough

Tyler

The airflow voltage reads just over 1v. The car is the same as a GA16 so pretty much the same. I am not sure what the fuel trim means by being absolute. Short term reads 100% absolute.

Do the long injection times only begin when it tries to switch to closed loop?

Andy.MacFadyen wrote: Do the long injection times only begin when it tries to switch to closed loop?

Exactly what I was wondering! The short term trim of 100% is a pretty good indication of open loop operation. A short term of 100% on a Nissan is the equivalent of 0% trim for everyone else.

I'd be interested to know how the fuel trims and upstream O2 react when the vehicle transitions from running well to running poorly, as well as any Loop Status PIDs. It sure sounds to me like a sensor input is changing drastically when the symptom happens...

Thanks for all your comments. Turns out the screws where slightly loose on the airflow meter. Heat and vibration as scanner Danner would say.

dnwof wrote: Thanks for all your comments. Turns out the screws where slightly loose on the airflow meter. Heat and vibration as scanner Danner would say.

Interesting! So the airflow meter was vibrating in it's mounting? I could see that causing a measurement problem...

Throwing the [FIXED] label on this one.