IDLE problem: rough and misfiring warm engine
09-11-2014, 01:11 PM
#1
Instructor
Thread Starter
Join Date: Jan 2012
Location: ITALY
Posts: 222
Likes: 0
Received 0 Likes
on
0 Posts
IDLE problem: rough and misfiring warm engine
A friend of mine has an '86 951.
From cold the car is fine, but after warm up the idle is rough, many misfiring and often shut off.
We changed RPM and REF sensors, engine coolant sensor, cap and rotor, spark plugs, and checked for vacuum leaks.
What else?
From cold the car is fine, but after warm up the idle is rough, many misfiring and often shut off.
We changed RPM and REF sensors, engine coolant sensor, cap and rotor, spark plugs, and checked for vacuum leaks.
What else?
09-11-2014, 04:01 PM
#4
Still have the stock AFM?
Years ago I had an issue with mine - the door inside was sticking. Caused sputters and stumbles once the car warmed up, as idle speed was lower once warm so the door was operating in a sticky area.
Years ago I had an issue with mine - the door inside was sticking. Caused sputters and stumbles once the car warmed up, as idle speed was lower once warm so the door was operating in a sticky area.
09-11-2014, 11:55 PM
#5
Rennlist Member
Maybe a sticking/gummed up ICV? Has it been removed/cleaned with [something like] carburetor cleaner?
Trending Topics
09-23-2014, 02:40 PM
#9
Instructor
Thread Starter
Join Date: Jan 2012
Location: ITALY
Posts: 222
Likes: 0
Received 0 Likes
on
0 Posts
Today i try to set the idle bypassing the ICV as per clark's, and i can set the idle at 840 rpm.
The car now idles fine but if i press the throttle a little bit the engine stumble and misfire ONLY between 1200 and 1500 rpm. With this problem the car is not drivable.
For remind:
RPM and REF sensors checked and adjusted
TPS checked and adjusted
AFM checked
TEMP sensor checked
SPARK, WIRES, DISTRIBUTOR and rotor new
Vacuum leaks checked
SWAP Klr & DME from other car DONE
What else should i do?
The car now idles fine but if i press the throttle a little bit the engine stumble and misfire ONLY between 1200 and 1500 rpm. With this problem the car is not drivable.
For remind:
RPM and REF sensors checked and adjusted
TPS checked and adjusted
AFM checked
TEMP sensor checked
SPARK, WIRES, DISTRIBUTOR and rotor new
Vacuum leaks checked
SWAP Klr & DME from other car DONE
What else should i do?
09-23-2014, 06:07 PM
#10
Today i try to set the idle bypassing the ICV as per clark's, and i can set the idle at 840 rpm.
The car now idles fine but if i press the throttle a little bit the engine stumble and misfire ONLY between 1200 and 1500 rpm. With this problem the car is not drivable.
For remind:
RPM and REF sensors checked and adjusted
TPS checked and adjusted
AFM checked
TEMP sensor checked
SPARK, WIRES, DISTRIBUTOR and rotor new
Vacuum leaks checked
SWAP Klr & DME from other car DONE
What else should i do?
The car now idles fine but if i press the throttle a little bit the engine stumble and misfire ONLY between 1200 and 1500 rpm. With this problem the car is not drivable.
For remind:
RPM and REF sensors checked and adjusted
TPS checked and adjusted
AFM checked
TEMP sensor checked
SPARK, WIRES, DISTRIBUTOR and rotor new
Vacuum leaks checked
SWAP Klr & DME from other car DONE
What else should i do?
09-24-2014, 08:19 AM
#12
Instructor
Thread Starter
Join Date: Jan 2012
Location: ITALY
Posts: 222
Likes: 0
Received 0 Likes
on
0 Posts
I checked ignition at the primary of the coil with a LED and from 1200 & 1500 rpm there are firing missing. What can i do now? I havn't an oscilloscope to check the rpm and ref sensors
09-24-2014, 11:54 AM
#13
09-24-2014, 11:56 AM
#14
Also they are easy to remove and clean, most times they get covered in clutch dust but I doubt that's the cause, doesn't hurt to wipe them up though