New to the forum so hoping I'm in the right place for some advice on a a throttle response failure on my 2004 S Type 2.5 petrol V6.
I lose throttle response and have to stop by the roadside, turn off the engine then wait for 20-30 seconds. I restart the engine and all is well for 2-3 days before the same problem.
No engine light or codes. The MAF sensor has been cleaned, maybe it needs to be replaced?

 

Welcome to the forum Dyna103,

I've moved your post to the S Type section, don't forget that intro in the new members section.

 

Norri, do I start a new thread in the New Members Intro?

 

Yes to the intro thread.

No red/orange light on dash & no messages?

Worth reading the codes - including pending ones.

 

 

 

Generally, when attempting to diagnose any issue such as this, it's best to ensure the battery is in good nick.

With the ignition off for at least ten minutes, the battery should have a minimum of 12.6 volts when measured across the terminals with a voltmeter. If not, charge the battery overnight and retest. If the voltage is still less than 12.6 volts, the battery should be replaced.

Many random DTCs and other warnings on the instrument cluster are caused by a failing or weak battery.

 

 

Please define "battery checks out ok".

Did you take the voltage readings suggested by NBCat in post #7 above? Or did you have it tested at a parts store or repair shop?

The reason I ask is we've had several examples where a battery passes a generic health check designed for a wide range of vehicles, but continues to cause oddball problems. I guess you could say the standards for an S-Type battery are much stricter than most cars. If your battery passes the typical test at a parts store or repair shop, it still may not be up to snuff.

Don't just rush out and buy a battery on a whim, unless the existing one is of dubious heritage. Take the voltage readings exactly as previously described. If good, try hooking up a charger every night for a few weeks and see if the car behaves. I realize it's a nuisance to do every night, but it's free and will really help narrow down the fault.

 

 

All right, making some progress!

14.7v means your alternator is working. On 2003+ models, you should see about 14.5v for the first few minutes, followed by dropping to approximately 13.5v. Maybe run the engine for a few minutes to make sure you're getting the required drop to 13.5v. If the charging voltage stays high, your battery may be getting cooked.

Per post #7, a prestart reading of 12.14v is too low. Charge the battery overnight, let it rest for at least 10 minutes, and then measure again.

Keep us posted, please.