| Author | Message | ||
     CHO SHU PUI DANNY New User Username: dnadanny1 Post Number: 16 Registered: 05-2019 |
Hi there. My car is installed with cat and oxygen sensor. (VIN: SCAZS02A5PCH46132) I feel the acceleration response is a bit lagged behind. When I use exhaust analyzer to measure, the lambda is between 1.03 to 1.05. And, I want to make it richer to 1.00 to 0.999. After I adjust 1/4 round clockwise of the mixture adjuster using 3mm allen key, the lambda does not change. Therefore, I think my approach is wrong. Is anyone here can correct me or suggest a better approach for me ? Any comment is appreciated. Thanks, Danny | ||
| Omar M. Shams Prolific User Username: omar Post Number: 1921 Registered: 04-2009 |
Dear Danny, Your 1993 car does not allow you to make changes to the fuelling characteristics. The whole fuelling schedule is pre-mapped. I don't know where you are making your adjustment - but I will assume that you are only adjusting the idle mixture. These cars are not rockets on wheels, but neither are they slow. If you have experienced deterioration in acceleration - you need to look at other factors. Could your catalytic converter be choked? is the transmission functioning as it should? are you starting in first gear? what has changed since you have noticed the deterioration in performance? | ||
| CHO SHU PUI DANNY New User Username: dnadanny1 Post Number: 18 Registered: 05-2019 |
Thanks a lot for your help. The car has made no change before. One year ago, when I picked up at the traffic light, there is a slight vibration from the engine for about 1/10 second before the acceleration. the vibration is to small that i dont even pay attention. However, recently the vibration is getting noticeable. When I open the bonnet to check the engine picking-up, the engine does vibrate for 1/10 sec before acceleration. Therefore, I think it has something to do with the mixture. http://rrtechnical.info/sz/cs/tsd5069p3.pdf As i want to correct idle mixture you suggested according to the link above, I dont understand item 8 and 9 on page 62. Could you explain it more to me? And, what parts or devices you recommend me to go check first? I have replaced distributor rotors, ignition wire, spark plug for this issue, but cant see any improvement. Thanks again for your help. Regards, Danny | ||
| Omar M. Shams Prolific User Username: omar Post Number: 1923 Registered: 04-2009 |
Dear Danny, Page 62 from the link above details the idle mixture only. That should not need to be changed if you have not made significant changes to the fuelling system. Yes you have replaced ignition parts - but how many times have people replaced spark plugs with new components that have failed within hours of installation? Spark plugs do fail and i have experienced that myself several times. The only way is to take the plug out and test it with the engine running using a spare plug to fill the hole. When you see the plug actually sparking - you will know that the cylinder is getting the spark it needs. If all 8 cylinders are sparking - I would then look at the ignition timing to see if that has changed. Next I would look at all vacuum hoses/lines to see if any of those have leaks. Finally I would look at the injectors to see if any of them have deteriorated. Good luck Danny. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 1924 Registered: 04-2009 |
Is the distributor cap in good order? | ||
| CHO SHU PUI DANNY New User Username: dnadanny1 Post Number: 19 Registered: 05-2019 |
Thanks a lot. I will individually test the spark plugs tomorrow. And I will replace distributor cap. And, i will use smoke testing to see if an y vacuum leak. I will keep you post at once. Thanks again. Regards, Danny | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 285 Registered: 01-2014 |
Leave the mixture adjusting screw alone until all other faults are investigated. You really need to interrogate the Motronic ECU, follow the instructions in the link I previously sent you. Sometimes you need to hold the appropriate buttons down a few seconds longer than instructed to. If you absolutely can't get the fault codes then check the following: Fuel pressure. Check for vacuum leaks,smoke testing best way. Check throttle position switch for correct operation. Check EHA for correct operation. Does it stumble the same both when cold and warmed up? Where are you sampling the exhaust from? Have you run some fuel injector cleaner through the engine? Good idea to do that after checking electrical system of engine management. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 286 Registered: 01-2014 |
Also make sure the hole for the mixture adjusting Allen key is plugged as it will leak air and upset the mixture if left open after using the Allen key. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| CHO SHU PUI DANNY New User Username: dnadanny1 Post Number: 22 Registered: 05-2019 |
Hi there. I replaced 2 distributor caps, and its drive belts. However, i discovered I cant adjust the ignition timing of the distributors. And, the ignition timing is BTDC 10 degree. For the spark, the spark plugs are in good condition. And, there is no vacuum leak. Also, I replaced throttle position switch. For exhaust sampling, I take sample from the end of exhaust pipe. According to the book, there is a copper nut cover on the right side of the engine near the front of exhaust manifold, where I can loose it by hand. When I start the car, there is some exhaust air coming out from the pipe. I think it should be the right sampling point. The CO result of idling is 9%! it is too high for that where the manual says it should be 1%. Then, I use Alley key to adjust it to 1%. However, the car it does improve anything. Much worser, the idling becomes obviously unstable. Could you please also advise what should I do to solve this issue? Thanks a lot. Regards, Danny | ||
| Omar M. Shams Prolific User Username: omar Post Number: 1931 Registered: 04-2009 |
I believe the post by UDO is worthy of a standalone post on "EHA - What it is- How it works - How to test it". Its a great write up and many would be able to benefit from it. Right now it is buried in the middle of this thread. Omar Great Suggestion - I agree and will do immediately. New thread has been created and is now accessible.  |
