hansvdweerd
Active Member
- Joined
- November 22, 2009
- Messages
- 81
- Reaction score
- 0
- City, State
- Vlaardingen, The Netherlands
- Year, Model & Trim Level
- '98 XLT (LPG conversion)
Hello all,
I'm hunting down an intermittent high idle problem with my 98 XLT 4.0 SOHC. I think I'm on the right track, but a little good advice might prevent me from buying parts that don't need replacing!
The problem hasn't shown up in quite a few months. Recently the weather here in Holland has been very foggy and between 0 en 8 degrees celsius. And boom! There it was again.
When I'm driving all is well. I love my car
When I decide to coast and the vehicle speed is dropping it almost seems like the RPM's don't drop fast enough.
When I'm about to come to a full stop the idle does not drop below about 900 to 1000 and sometimes not below 750. At that point I also hear a soft clung. I think that's the gearbox shifting down to first, but with the RPM's being to high I think it isn't too happy with it. Normally I don't hear this sound coming from my transmission.
After driving on for a while most of the times the problem goes away. I cleaned the IACV a few months ago and the problem stayed away for some time.
Recently I changed the TPS sensor and the IACV-gasket. I have no DTC's (I check this myself with my laptop). The absolute throttle position is 20%.
Now here's the thing:
When the idle was high in D as well as in P I decided to unplug the electrical connector to the IACV. That is with the engine running. The RPM's dropped to about 350-400. When I plugged it back in again the idle was perfect (650-700 RPM in P). I repeated this a few times more that day when the problem occured again and it worked every time.
My question:
Should I throw a new IACV at this problem? My last IACV dates back some two years and about 45.000 km (25000 miles I think). Could it be that the IACV sticks open a bit now and then?
Any input is greatly appreciated!
Kind regards,
Hans
I'm hunting down an intermittent high idle problem with my 98 XLT 4.0 SOHC. I think I'm on the right track, but a little good advice might prevent me from buying parts that don't need replacing!
The problem hasn't shown up in quite a few months. Recently the weather here in Holland has been very foggy and between 0 en 8 degrees celsius. And boom! There it was again.
When I'm driving all is well. I love my car
When I decide to coast and the vehicle speed is dropping it almost seems like the RPM's don't drop fast enough. When I'm about to come to a full stop the idle does not drop below about 900 to 1000 and sometimes not below 750. At that point I also hear a soft clung. I think that's the gearbox shifting down to first, but with the RPM's being to high I think it isn't too happy with it. Normally I don't hear this sound coming from my transmission.
After driving on for a while most of the times the problem goes away. I cleaned the IACV a few months ago and the problem stayed away for some time.
Recently I changed the TPS sensor and the IACV-gasket. I have no DTC's (I check this myself with my laptop). The absolute throttle position is 20%.
Now here's the thing:
When the idle was high in D as well as in P I decided to unplug the electrical connector to the IACV. That is with the engine running. The RPM's dropped to about 350-400. When I plugged it back in again the idle was perfect (650-700 RPM in P). I repeated this a few times more that day when the problem occured again and it worked every time.
My question:
Should I throw a new IACV at this problem? My last IACV dates back some two years and about 45.000 km (25000 miles I think). Could it be that the IACV sticks open a bit now and then?
Any input is greatly appreciated!
Kind regards,
Hans
