Having some cold start surging..

[Damon88]

Spent about an hr going through old posts on this topic. No farther ahead than I was when I started... Just purchased the car recently. I have gone through ands checked for air leaks. I just ordered a CIS fuel pressure gauge, but with holidays it won't be here until mid January. Service records show it had fuel pump, check valve & fuel filter replaced. When cold I have to give it a little gas to start. After roughly Two to Three minutes, it idles fine. Tonight I will read more about CIS systems. Any suggestions on things I can check until my gauges show up would be greatly appreciated. Cheers.

https://youtu.be/DpERBLOYGXw

[targa80]

Have you been to Jim’s basement workshop website. It provides a wealth of info on the CIS system. There is a troubleshooting chart that provides faults and possible causes.

Also do a search for CIS for dummies on this site.


https://www.jimsbasementworkshop.com/CIS/pages/test_troubleshoot.html#lambda

[Damon88]

Originally Posted by targa80

Have you been to Jim’s basement workshop website. It provides a wealth of info on the CIS system. There is a troubleshooting chart that provides faults and possible causes.

Also do a search for CIS for dummies on this site.


https://www.jimsbasementworkshop.com/CIS/pages/test_troubleshoot.html#lambda

That's great info !thank you for that. I will check both links out. Cheers

[Ian Comerford]

You shouldn’t need to give CIS any gas to start from cold, which 8ndicates something is not right. You should also avoid this because it can cause a backfire and damage to your airbox, I learnt this a couple of months after buying my car 23 years ago…..

[mikedsilva]

Originally Posted by Damon88

Spent about an hr going through old posts on this topic. No farther ahead than I was when I started... Just purchased the car recently. I have gone through ands checked for air leaks. I just ordered a CIS fuel pressure gauge, but with holidays it won't be here until mid January. Service records show it had fuel pump, check valve & fuel filter replaced. When cold I have to give it a little gas to start. After roughly Two to Three minutes, it idles fine. Tonight I will read more about CIS systems. Any suggestions on things I can check until my gauges show up would be greatly appreciated. Cheers.

https://youtu.be/DpERBLOYGXw

I'm no expert, but hopefully Tony and others will chime in.
Yes, you need your fuel pressure tester before you can get any useful info.

Also, I found that a wideband sensor was very helpful to ascertain my AFR.

If it is running poorly (while warming up) you might be able to get an indication of if it is too lean or rich by removing the airbox cover and filter, and then either applying downward or upward pressure to the sensor plate arm. If you lift it, it will add fuel and richen the mixture. If it runs a little better, it might indicate you are running a little lean. If you push down to slightly lean the mixture, and it runs better, then perhaps you are a little rich while warming up.

Either way, you will need to check your pressures as per below...

Definately watch this video and others from this channel.. lots of REALLY good info.

[proporsche]

It sounds to me you are running a little rich.As said never step on gas pedal while starting the 911 .You air box will explode ....

Also you should address the noise valve adjustment..

Ivan

[Damon88]

Originally Posted by mikedsilva

I'm no expert, but hopefully Tony and others will chime in.
Yes, you need your fuel pressure tester before you can get any useful info.

Also, I found that a wideband sensor was very helpful to ascertain my AFR.

If it is running poorly (while warming up) you might be able to get an indication of if it is too lean or rich by removing the airbox cover and filter, and then either applying downward or upward pressure to the sensor plate arm. If you lift it, it will add fuel and richen the mixture. If it runs a little better, it might indicate you are running a little lean. If you push down to slightly lean the mixture, and it runs better, then perhaps you are a little rich while warming up.

Either way, you will need to check your pressures as per below...

Definately watch this video and others from this channel.. lots of REALLY good info.

Thank you very much Mike for chiming in. Very helpful. I will sneak into the garage today and remove the air box and give it a go. All the best pal.

[Damon88]

Originally Posted by proporsche

It sounds to me you are running a little rich.As said never step on gas pedal while starting the 911 .You air box will explode ....

Also you should address the noise valve adjustment..

Ivan

Ivan, Thank you for taking the time to respond. I'm glad you posted this.I had no idea about the stepping on the gas pedal while starting car. I know the air box has the pop of valve installed. But I will now leave the pedal alone.. hah

service records show the car had a valve adjustment not that long ago.. but I will look into this more... much appreciated.

[Damon88]

Originally Posted by Ian Comerford

You shouldn’t need to give CIS any gas to start from cold, which 8ndicates something is not right. You should also avoid this because it can cause a backfire and damage to your airbox, I learnt this a couple of months after buying my car 23 years ago…..

Thanks Ian. Ivan also pointed this out. I had no idea.. Note to self... leave gas pedal alone while starting.. hah Cheers bud.

[proporsche]

another trick to find out if you are running rich is ,put the a/c on and step on the gas a little if the car dies with the air on it is too rich
Also make a little video after the engine is running even to listen to that noise,hoping it the valve adjustment and not the chain tensioner