Hi there,

I'm having some troubles with my 97/98 3.2l... Only when cold.

The car fires up instantly. And runs well. Once the idle sets at around 1000 rpm (cold) the engine runs a little rough and it lacks power. The power then comes in 'bursts'. If you floor it, the engine will slowly gain revs untill around 2500 rpm and then all is good again.

Once driving there is nothing no be noticed. No power shortage nor lumpy running. When warm, the car will start perfectly and run perfectly.

These problems have been getting worse and worse lately. After fitting a new Bosch oxygen sensor the syptomes whilst driving went but that was a different problem.

For the records: there are no codes saved in the ECU. The problem only occures when cold. The fuel consumption hasn't lifted nor can anything else (other than the odd 'nod' like a misfire or stumbke) be felt when driving.

Where would you start looking?

Cheers

Damien

 

Coolant temperature sensor? Usually that would also cause a hard start condition, but my reflex when anything happens ONLY when the engine is cold is to check the CTS.

 

As said, it starts up instantly... Is that the sensor on the front pipe between the two banks (the pipe going to the radiator)? Or does the engine-relevant one sit somewhere else?

Cheers

Damien

 

Yes, it sits up front on the coolant pipe between the two banks. Extremely easy to change; unplug it, unscrew it and simply put in a new one. But, like you said your car starts up instantly, so I was just adding my 2 cents.

I always change that item on any car I buy because it's cheap, easy to replace and it's a critical source of information for the car computer system. The ECU calculates a lot of other parameters based on engine temperature, as I understand it...

 

Sounds like common sense. For a mere €12 I'll buy one. Can't hurt.

 

Maybe invest in a new MAF sensor, as well. Pretty cheap replacements now available on the web.

 

Jim, can you link me to a cheap MAF replacement? I wanted a new MAF for the 03 XJR, but all I could find were rebuilt ones for $125, new ones for $250 ish and Chinese ones that take 1-2 months to ship. The Chinese ones claim to be OEM, but I've read some reviews that said otherwise.

 

My 2 cents would be a weak battery, especially if the problem is cold related. Revving to 1500 pushes up the alternator output and the gremlins go away. The battery may be sufficient to start but the electronics need more than is available and once the alternator charges up the battery everything will settle out until next time.

 

Battery is totally fine. It is a huge'n and is about 2 years old... I can crack the engine over for hour before that is dead

Regarding the MAF thingey... Worth a try. I'll start simple and work my way up. Thing is, it now backfires/misfires when in D (under load) when cold from an initial start up. Out in N, floor it, and it works like new again... Lambdasonds are fine... The problems got worse as one of them died. Replaced and they got better.

 

D: I think it is the coolant sensor (maybe a crimped wire even, between the sensor and MAF).

Harvest: found the inexpensive MAF on Amazon, but it was for an NA engine, not SC: not sure if there is a difference. Unit I bought was made in Japan, brand new. Pull the Denso code and run a search.

 

Okay, I replaced the temperature sensor... No change what so ever... Just that my fans were then always running... I am starting to hate this car. I have never hated a car before but I am not far from setting it on fire.

 

Fans running on is usually a dead T-stat. Try and feel if one side of the rad hose is hot, the other cold. Or you can test the T-stat.
It's an odd one, maybe an unmetered air leak from a gasket, have you had the throttle body off at all?
Coils can go intermittent before they die, but generally post a code.

My suggestion-check for oil in the plug holes, I've had this type of misfire from leaking plug seals on the cam covers when the oil got hot enough the misfires went.

And for the record, I know the feeling, I've had epic arguments with Jaguars'

 

Thermostat is fine. Radiator heats properly. The fan would always run - even on an ice cold engine with the new sensor. Old one in, engine runs at around 98°C. So all fine.

Gasket problems would always be there all the time... Not only when cold.

I'm trying a different battery, as it may cause it... The current battery is okay but the one before was younger (though smaller).

Plug holes are oilfree... New gaskets were fitted around 3 months ago...

 

(Thermostat is fine. Radiator heats properly. The fan would always run - even on an ice cold engine with the ew sensor. O,d one in, engine runs at around 98°C. So all fine.)

I don't understand that fan should run when cold with new sensor.

 

The sensor, though being brand new and from Bilstein, was f**ked. The old one would engage the fan, every so often, bit not all the time. The temperature gauge though worked normally... The old Denso sensor is in again and everything is fine... Except the cold atart niggles are still there.

 

How new is the fuel filter and pump? Still, thinking it is a bad MAF. If it was anybody else (I know you have done there on many cars), I would suspect poor timing.

 

Fuel filter and pump are both old. But both work fine. Especially because kt doesn't matter of on LPG or normal E10.

 

Oh, sorry, forgot you remodeled the car. My guess is you need to find a tech who is really knowledgeable on LPG conversions. One of the members in romania did it a few years ago and had some fun sorting it out.

 

The gas System is running well. I think it may also be a faulty MAF... But that'll have to wait... Other expensives come first...

 

So I fitted a new old battery on Sunday. Power is all fine. I guess the battery might actually have been at fault... The old one has a steady 12v holds it's charge and has loads of amps... But maybe a dead cell...