Yesterday I started my Z, let it run for a minute then when I started to drive I noticed that when the tach got near 4krpm or I press the gas more than 25%, my car starts to loose power, like Im pushing the gas and it is not reving any higher and then it will suddenly kick in for a second then loose power again, jerking me around in the **** pit. WTF. This happens when the car is cold or sits for more than a few hours and remedies itself(for now) when warm. Anyone know what would cause this? There are no idiot lights or anything and Voltage and Oil Pressure is normal. Any help is appreciated.

 

check you spark plugs and associated wiring. Sounds like one of your plugs is not firing properly

 

Would this cause the problem when cold and somehow remedy itself when warm?

 

I do not know the answer to that question.

 

More Help Please, before I go nutz worrying about it. I dont know when I can get to the dealer as they will need a few hours with it to get it cold and it is my daily driver so with out it I am SOL and cant miss work. HELP.

 

Mines done this twice in the last 6 months. As soon as it hits 4k rpm it acts like it wants to die. Ive tested it in 1st-4th gears and each one will do it. I just turned it off, turned it back on and it was fine. At first i thought it was some kind of vallet mode or something. If you take it in and they fix let us know!

 

I will be taking it in, just need to figure out when I will have the time. Hopefully its nothing too major. Dealer thinks from my description, it could be Engine Management or Fuel delivery issue, both sound scary to me but what do I know.

 

It would be nice to go for 1 full month with out a single Z related problem.

 

A faulty coolant temp sensor (NOT the gauge sender).

If the ECU doesn't know the engine is cold (input from the coolant temp sensor) it won't prrovide the correct A/F for a cold engine. That's why it runs ok when it warm up...the A/F is then correct for conditins.

bill

 

It happened to me as well. It was 95-100 degrees out and I boosted to about 4500, my car lost all power and began to sputter. I shut car off and when I restarted ,it was fine. I went to my tuner and they told me it went into limp mode. It is a safty mode and it costs alot to over ride it.

 

Limp Mode??? Cost Alot??? Please elaborate

 

MAF?? (Mass Air Flow sensor)

 

My pop Charger is DIRTY but MAF issues usually arise from over oiling the filter and the oil getting on the sensor, correct me if I am wrong. Not to mention the problem seems to resolve itself once the car is warm. This is what makes it so difficult for me to figure it out. with the loss of MPG along with the way it bogs I believe it to be related to fuel delivery but again, how could it resolve itself when the car gets warm? There are no Idiot Lights coming on either and all guages are normal. Spark plugs should throw a light as I think MAF would also. Someone mentioned a Faulty Coolant Sensor and that it may not know the car is cold so it is confusing the ECU but when it is warm its all set cause the faulty sensor thought it was warm to begin with. I guess that makes sense but really its just somthing else for me to mention to the dealer as a possibility cuz Im no mechanic or engineer. Also would a faulty Coolant Sensor throw a light? Thanx for all the help guys, I love my Z through the good times and the bad times, but a community like this really make the bad times alot easier to handle...thanx again to anyone who has ever responded to a post or thread of mine

 

I forgot about this. To test the sensor, you'll need a fluke meter, small pot of water and blow dry. Sensor resistance should should accordingly as water temp changes. If resistance doesn't change, the sensor is defective.

 

Could you please explain this a little better?

I think I can understand what bailey bill wrote about a faulty temp sensor. The only other thing I can suggest is either clean the MAF sensor and/or reset the computer by disconnecting the battery.

Thanks.

 

How many miles are on the car?

Have you replaced your thermostat yet? The thermostat should be replaced about every 30k miles. Also, do not use a colder thermostat than stock. Has your coolant been flushed before? Considering you have an '03 I'm sure you have been due for a flush or two. Old coolant can gunk up the coolant sensor. Have you checked your coolant level? Do those things first if not.

With those things done (if necessary)....

To test a coolant sensor all you need is an ohmmeter. While the engine is cold, (make sure the ignition is off) disconnect the wires to the sensor and measure the resistance at the sensor. Reconnect the wiring and start the engine and let it run for a few minutes to warm up and then turn it off and check it again. I'm not sure what the exact specs are with our Z (should be a difference of several hundred ohms). If not you can try removing the sensor and cleaning it and repeating the test. You can also use a voltmeter and measure the differences in reference and return voltages.

Clean your air filter regardless.

 

06Firebase, this would be the easier method of the 2 to perform. My method was to measure precise resistance readings when the temperature is variated. But of course, you'd need to know exact specs at exact temperatures. This is what the blowdryer is for. To heat the water, thus heating the sensor. Water temperature can be measured. You'd be better off using Roast's method though. Then again, if you're unfamiliar with electronics, DMM's, or mechanical work you'd be better off just taking it to a mechanic.

 

The car has 62k on it but the engine and tranny were replaced at 52k so the flush would have been done then.

Thermostat has not been changed as far as I know so I will have them check that.

Yeah I need to clean the filter. I did it 2 months ago but then I drove it to Boston and back and killed every bug in the country along the wayso there are lots of carcasses in my filter. I just dont want to clean it before they check it out. I will clean right after though.

As far as testing it myself, I only clean my filter, THATS IT. I took the engine cover off once to install a grounding kit and dropped a waser into the pullies and after that I decided not to take the car apart again.

Hopefully tomorrow I find out its a cheap and quick fix so I dont miss the Hurst Castle run on Saturday.