Blinking CEL but no Fault Code

[xiaogary]

I just went for a tuning session last night after installing lightweight camshaft pulley and 2 inch straight through exhaust. The car is more powerful now, especially the higher ends which I can feel the exos gas filling the 2 inch pipe more rapidly and more back pressure to pull the car forward. On the 20km trip back, can feel the extra power. No problem at all.

But the engine check light started blinking this morning after 10km travelled when I rev it to 150km/h from 90km/h on a upslope hill climb to feel improvement of the tuning as this is the road I have been travelling everyday. There is no knocking or detonation that I can feel. No strange noise also.

The CEL started to blink at abt 140-150km/h and no other obvious strange thing is happening except of the blinking CEL. I have a Scangauge II in my ride which is already plugged to my OBDII port. I immediately scan it while slowing down the car to 100km/h. No code surfaced from the scan. I stop one corner, off the engine, on it again and scan it again, no code also. Off 2-3 time, scan again, no code also. But once engine started, the CEL is blinking.

Is there some codes that Scangauge cannot read? How to know whats the problem? There is no power cut or speed cut or whatsoever. The ride still feel as powerful even after the CEL starts blinking. Although I slow down to 100-110km/h, it still blink. Then stop, idle for 1 min, travel, still the same. Never stop blinking since it started blinking.

Is it safe to continue driving to the workshop after I off work abt 8 hours later? It blink slowly, like frequency of every one second. Not fast blinking. No double blinking or quick blinking. Only normal slow blinking.

[GsiTurbo]

According to what I read in the manual for the Optra/Lacetti a while back (I would have to find that section again), quick flashing of CEL indicates pinging. For me, it was occuring under heavy acceleration. I'll try to dig out that section and post it here.

[Daniel]

It blink slowly, like frequency of every one second.

From service manual:

"Special Cases of Type B Diagnostic Tests
Unique to the misfire diagnostic, the Diagnostic Executive
has the capability of alerting the vehicle operator to potentially
damaging levels of misfire. If a misfire condition exists
that could potentially damage the catalytic converter
as a result of high misfire levels, the Diagnostic Executive
will command the MIL to flash at a rate of once per second
during those the time that the catalyst damaging misfire
condition is present."

Do you still have a catalyser?

Daniel

[exist3nce]

I would second the misfire code, I have seen the blinking on mine in the same manner and it only happened during misfire. I was able to scan the code while the light was blinking, but after it turned off (about 5mins later) there was no code. The code I got was P0300 - Random Misfire.

[xiaogary]

Hi Firstly thanks for all the replies. Appreciate it a lot.

I do not have a Catalyst in my car. My exos setup is Long 4-1 header, original 3 nuts flange with fexible pipe, 2 inch mid pipe with Hotbits straight through mid muffler/silencer and 2 inch rear Super Dynamics Muffler. Sometimes changing the rear to Remus 2 inch straight through muffler or Berklee 2 inch straight through muffler.

I have a Scan gauge in my car, no codes while CEL is blinking. I have P0300 occasionally every now and then about once every 3 days of driving ever since the rebuilt of the engine with high compression piston 11.1:1 with bored and stroked up to 1680cc. But this time round, there is no code although CEL is blinking.

I had once the whole engine jerk badly 2 months back few days after the engine rebuilt (during run in after tuning) due to misfiring because one of the injector was not clipped properly and came loose. That time P0300 surfaced and car jerk violently and keep dying off during idle, have to step a lot of petrol to maintain idle just like faulty spark plug. But this time round, everything was calm, no strange jerk. Only blink CEL. I cannot remember whether CEL was blinking quicker or slower during this loose injector incident or same like now, 1 sec frequency.

After off work today, about 12 hours later. I started the engine, no CEL. No code. Happily, I drove off but after abt 20+km and 20 mintes of driving, the CEL came blinking again, nothing strange observed from engine. Still as powerful, still as smooth, but blinking CEL at 1 sec frequency, same as morning.

Drove to my tuner 5 minutes away, and he said this is due to the advance in timing he set in my UNICHIP (piggyback) is an additional 2 degree for certain rpm range. He just tuned my car the night before. He said there is a protective or alert system in the original ECU which detected the advance in ignition timing and deem it "unsafe or attention required" by raising a CEL blinking status. According to him, its a safety feature, no additional actions will be taken by the ECU for most cars. However he added that some vehicle will add extra petrol during this blinking CEL for safety. He asked me to monitor the Fuel Consumption and try to pump higher octance petrol to see whether its due to knocking pinging or misfiring. I am currently on Shell 98. Looks like I need to pump shell 100 also known as Vpower to try.

I will drive to work tomorrow morning, which is 4 hours from now (2am now). I expect the CEL to be blinking after 15 min of driving. Hope its like what my tuner say that there is no adverse effect other than the alert system. He tuned 2 degree more advance for certain rpm range during last night tuning on top of the advances he created in the mapping previusly before I changed whole mid pipe to 2 inch and change the 2 cam pulley to lightweight cam pulleys which are 40% or the weight of the original pulleys. Indeed, cars feels faster with the additional advance. I can feel the exos gas filling the exos faster, thereby feeling the back pressure faster (less lag) during acceleration. But hope I can continue to drive in such condition safely.