Based on what you reported, the MAF would be the first thing I'd check... it's not very difficult at all to clean them.

 

BINGO! Plus check fuel pressure since its only during hard acceleration, sounds like one of the pumps might be backfeeding the other....witch will give you a total system pressure of about 30-35 psi needed is about 50-55psi witch means under light acceleration your good but under heavy you just dont have the correct volume of fuel

Eddie Rodriguez
562 650 1732

 

The vent valve is a common failure in these cars, I don't see it causing your issue though.

Pull the spark plugs and have a look at them.

 

Thanks to all who replied (very helpful)

You know, this whole thing started after a fill-up. I read some similar stuff on the forums about people having problems after fill-up. Most would default (for good reason) to the idea that it would have had something to do with the fuel quality. I think the pattern reveals that something else is going on, something that I also read about on this forum.

You know, if you don't turn off the ignition switch before pushing the fuel-door release button in the glove-box, the ANTIEVAPORATION system reacts to this in a way that causes the Gas Station pump to shut off continuously as if the tank is full even though it is not. It also seems possible that this sequence of events could also disturb some sensitive check-valves in line or down stream, causing issues that could effect how the car is running and throw codes as well. (CRAZY)

I will be keeping my eyes on this as I continue the diagnostics on what could be (as often is) in the world of auto-repair, a multi teared matter of multiple systems failure.

MAKE SURE YOU SHUT OFF YOUR IGNITION SWITCH BEFORE PUTTING GAS IN A MASERATI.

 

MAKE SURE YOU SHUT OFF YOUR IGNITION SWITCH BEFORE PUTTING GAS IN A MASERATI.

You should turn off the car before putting gas into any car!

 

I think 02Maserati meant to say to make sure to shut off your ignition BEFORE pushing the fuel door release button.

 

I'm sure there could be many reasons.

In my case, why the f*ck I did not shut off the "IGNITION SWITCH" not the car but the "IGNITION SWITCH" is because, I was listening to a good old LED ZEPPELIN tune on my SIRIUS radio and wanted to continue listening while fueling up. So, the ignition switch needs to be in the accessory position in order for the SIRIUS receiver to be powered up.

 

In my case, why the f*ck I did not shut off the "IGNITION SWITCH" not the car but the "IGNITION SWITCH" is because, I was listening to a good old LED ZEPPELIN tune on my SIRIUS radio and wanted to continue listening while fueling up. So, the ignition switch needs to be in the accessory position in order for the SIRIUS receiver to be powered up.

Lol. I've done that before on several vehicles, and would never have guessed that it could cause an issue in a car. Good to know.:cheers:

 

Lesson is: Led Zep is cool, but properly fueling up your car without causing any issues is cooler.

 

Thank you. Just call me Sensei.

 

Someone chime in here, but I think the Coupe's have two seperate fuel pumps. One is used under light acceleration and idle, the other during heavy acceleration.

 

I didn't know this. Can someone confirm? This would definitely be essential to know in troubleshooting similar problems in the future.

 

Under moderate and especially under hard acceleration when the engine is calling for fuel and air, this 28,000 mile O.E.M. equipped, 02 coupe, 6spd. misfires with extreme loss of power while pinging in the exhaust, nasty detonation. CODES: P0300, P0301, P0302, P0303 and P0304 all agree with my ear that miss-firing is going on. Question is what is causing the misfiring which never happens under very light load or acceleration (minimum C.F.M.).

QUOTE]

The answer maybe as simple as someone put Regular gas when you had your last fill up. The station may have had Regular gas pumped into its Premium tanks.

Wait till your next fill up and go to a staion with one pump hose ofr each grade of Gas, and make sure you are getting High Test only.

 

Already eliminated that prior to posting. Right now I have in my mind, fuel pressure, Mass air flow and spark plugs. I suspect that codes in which I have been receiving might be phantom codes. If I clear codes, the car will stay code free if I do not recreate the misfiring and power loss by driving the car under light load and rpm. The problem only occurs under moderate to high load/rpm thus throwing codes. I will change spark plugs first since there would be no codes for spark plugs (except for misfiring codes) which is kind of an after thought as far as the ECM is concerned. I will go on record as saying I have not spent a penny yet as far as part replacement is concerned. My first choice of diagnostic related part replacement will be spark plugs (Denso IU24) my guess is it will cure the problem. If not, I will move on to MAF and Fule Pressure testing. I will report my results to this forum.

 

cleaning the MAF is just as easy as changing plugs. id clean the MAF first. buy a can of MAF cleaner for 5 bucs then go from there

 

Not getting any MAF sensor codes.

Not getting any MAF sensor codes. I realize that MAF is still a potential suspect but it is a little telling that there are not any MAF codes at all. In addition, the car has only 28,000 miles. As admittedly simple as it sounds, a spark-plug diagnosis, this kind of scenario is known to happen sometimes, especially on hi-compression engines.

I will continue with the above mentioned protocol. I would like to see a fresh set of plugs in the car anyway. If not for routine maintenance, for deducing through an educated process of elimination thus creating a stable platform if there continues to be a need for diagnostics going forward.

 

Not getting any MAF sensor codes. I realize that MAF is still a potential suspect but it is a little telling that there are not any MAF codes at all. In addition, the car has only 28,000 miles. As admittedly simple as it sounds, a spark-plug diagnosis, this kind of scenario is known to happen sometimes, especially on hi-compression engines.

I will continue with the above mentioned protocol. I would like to see a fresh set of plugs in the car anyway. If not for routine maintenance, for deducing through an educated process of elimination thus creating a stable platform if there continues to be a need for diagnostics going forward.

02, i been thinking of installing the denso plugs myself. please let us know if u see a real difference

 

This could be applicable , recently posted on SM , re the fuel vapour system
valve getting stuck in the open position


Poor starting, especially when hot, even worse when filled with fuel



worth checking


regards loz

 

It was the God-dam Cats.

The primary cat on bank #1 grenaded and it's material lodged in the secondary cat down stream. Gutted both secondary cats, scoped the primary's in the manifolds with digital camera probe. Confirmed the cat for bank #1 manifold is an empty can and the cat in bank #2 manifold is intact and the only cat left in the car for now. I don't believe there is any restriction in the bank #2 manifold/cat, engine is running under safe conditions which is my main concern. The car is running like a raped ape, powerful as hell. I will gut the cat in bank #2 manifold and am definitely in the market for a pair of Larini sport-cats. I will reallocate the O2 bungs up and down stream of the Larini cats to satisfy the E.C.U. as now there is a steady cel light in the instrument cluster of course. Also, in the market for some valved cans and x pipe to complete the custom exhaust mod for this 02 coupe, 6 speed. I will add, I've worked on many an auto by many a manufacture in my time and it must be the best kept secret, this car is the easiest car I believe that I have ever had the pleasure to work on. The car was designed to come apart and go back together again. The Italian's did an unbelievable job and should be recognized for this build.

 

Good luck. Be careful with the O2 sensor relocation. It isn't as easy as it sounds and if you mess it up, ECU damage will occur. Once member here, FlashGordon, want through hell for a long time due to a botched job.

 

Damaged the ECU?



Was there ever a determination as to what happened with the flashGordan case?

The O2 sensor harness must have still been plugged in while being worked on and shorted, cross wired and or electrically surged by a soldering iron. I am planning to engineer the O2 harness on the bench with pre-measurements, fastening and proper shielding in mind. I will use solder connections and shrink wrap exclusively. I will consult with Jeff at formula dynamics on the construction of the O2 harness. I'm thinking, the wire of choice is probably very important in regard to resistance and it's ability to deal with heat, vibration and such.