Fuel injection woes

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colrich

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I'm hoping someone on the forum can help me with this or point me in the direction of a specialist in the UK.
On start up the engine runs fine and does so until it reaches normal operating temperature when the engine speed reduces to idle of about 600rpm, problem is it then will not rev above this without feathering the throttle pedal an then the revs rise only slightly but now it's not smooth but irractic, I'm guessing thus could be something to do with the air pressure sensor or throttle valve, any advice appreciated.
 
I can't offer corrective advise...but my original engine 73' CSi has a similar issue. It idles and starts fine; idle is strong and steady until the engine warms and (auto choke?) kicks off. Then it revs up and down but never stalls - and it will intermittently stop revving up/down and smooth out with no consistency. At one red light it revs up & down, at the next light it idles smooth. At first I thought it might has to due with the outside temperature but I don't think it does. It's a scary problem (for me) because in the US (I think) it will be hard to find someone that understands these engines. I hope we find an answer. Good Luck!
 
colrich said:
I'm hoping someone on the forum can help me with this or point me in the direction of a specialist in the UK.
On start up the engine runs fine and does so until it reaches normal operating temperature when the engine speed reduces to idle of about 600rpm, problem is it then will not rev above this without feathering the throttle pedal an then the revs rise only slightly but now it's not smooth but irractic, I'm guessing thus could be something to do with the air pressure sensor or throttle valve, any advice appreciated.
Click to expand...

At the base of the back under the throttle body, on the the firewall side, is a 2 cm screw. Back it out 1/4 of a turn to increase idle to ~900.



BikeRider said:
I can't offer corrective advise...but my original engine 73' CSi has a similar issue. It idles and starts fine; idle is strong and steady until the engine warms and (auto choke?) kicks off. Then it revs up and down but never stalls - and it will intermittently stop revving up/down and smooth out with no consistency. At one red light it revs up & down, at the next light it idles smooth. At first I thought it might has to due with the outside temperature but I don't think it does. It's a scary problem (for me) because in the US (I think) it will be hard to find someone that understands these engines. I hope we find an answer. Good Luck!
Click to expand...

Your CSi is "hunting" it's trying to balance the air fuel mixture. It could be your Manifold Atmospheric Pressure Sensor, Throttle Position Switch or the dial on the back of the ECU or a combination of those.

Advise calling Vintage Sports & Restoration in Bedford New Hampshire 603.228.2888.
 
adawil2002 said:
At the base of the back under the throttle body, on the the firewall side, is a 2 cm screw. Back it out 1/4 of a turn to increase idle to ~900.





Your CSi is "hunting" it's trying to balance the air fuel mixture. It could be your Manifold Atmospheric Pressure Sensor, Throttle Position Switch or the dial on the back of the ECU or a combination of those.

Advise calling Vintage Sports & Restoration in Bedford New Hampshire 603.228.2888.
Click to expand...
Good information...appreciate your reply...
 
colrich said:
I'm hoping someone on the forum can help me with this or point me in the direction of a specialist in the UK.
On start up the engine runs fine and does so until it reaches normal operating temperature when the engine speed reduces to idle of about 600rpm, problem is it then will not rev above this without feathering the throttle pedal an then the revs rise only slightly but now it's not smooth but irractic, I'm guessing thus could be something to do with the air pressure sensor or throttle valve, any advice appreciated.
Click to expand...
Your symptoms may be due to any of a long list of simple adjustments.

As already suggested, adjusting the big fat idle air adjustment screw at the base of the throttle body may offer some relief although it is unclear whether something else in the way of an adjustment has changed, e.g., points setting and/or ignition timing.

Since your issue seems to arise only after the engine reaches normal operating temperature, your cold start valve might not be fully closing and dribbling some fuel. This easily might account for an erratic idle and/or mid-range operation. Disconnecting the fuel source to the valve might eliminate this as a possibility.

You mention the need to feather the throttle when increasing engine speed. If this is more pronounced when accelerating (under load), your throttle position sensor could be worn or maladjusted. Your engine has two temperature sensors. When either or both are faulty/disconnected, this can cause or contribute to "erratic" running.

autobooks_manual_043.jpg


See also: https://jetronic.org/en/d-jetronic/72-troubleshooting#Kaltstartventil
 
I had this very issue and checked everything. I also changed the fuel pressure valve twice, all to no avail.

It turned out that the distributor was arcing across the connections on the inside. It was fine at idle but misfired when trying to rev it, or cut out completely. Before spending a lot of money, try taking the dizzy head off and inspecting the condition of the contacts and cleaning them up. It cured all my ills.

Where about in Cheshire are you? I have family there.
 
Rek said:
I had this very issue and checked everything. I also changed the fuel pressure valve twice, all to no avail.

It turned out that the distributor was arcing across the connections on the inside. It was fine at idle but misfired when trying to rev it, or cut out completely. Before spending a lot of money, try taking the dizzy head off and inspecting the condition of the contacts and cleaning them up. It cured all my ills.
Click to expand...
Distributors are wearable parts & weren't built to last 40-50 years. Highly recommend a 123 Distributor designed to work with D-Jet & purchase the helically milled spindle from the US.
 
Rek said:
I had this very issue and checked everything. I also changed the fuel pressure valve twice, all to no avail.

It turned out that the distributor was arcing across the connections on the inside. It was fine at idle but misfired when trying to rev it, or cut out completely. Before spending a lot of money, try taking the dizzy head off and inspecting the condition of the contacts and cleaning them up. It cured all my ills.

Where about in Cheshire are you? I have family there.
Click to expand...
I fitted a new cap and leads at the weekend, had it running for 30min, was revving ok so hoping might have cured fault, be surprised if it
was that though. still have the high idle until I clamp aav hose then it drops to around 700 rpm.
Ellesmere port.
Thanks for the advice
 
colrich said:
I fitted a new cap and leads at the weekend, had it running for 30min, was revving ok so hoping might have cured fault, be surprised if it
was that though. still have the high idle until I clamp aav hose then it drops to around 700 rpm.
Ellesmere port.
Thanks for the advice
Click to expand...
We are rebuilding AAV’s at the shop again….

LMK
 
Disassembled ….
 

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