Slight surge

[V8Landy]

I have a slight surge in my 3.9V8i on gas. Ihave changed my converter and had mixtures checked. It is still surging and only seems to be on gas at cruising speeds from 40-80 kms approx. What is the next thing to look at?. any info would be appreciated.:confused:

[PAT303]

Does it run a high idle?.Mine did a similar thing and it was the stepper valve on the plenum. Pat

[V8Landy]

Does it run a high idle?.Mine did a similar thing and it was the stepper valve on the plenum. Pat

I have had the stepper disconnected up until i put the converter on. Maybe i will try and disconnect it again but the idle has been ok just a little slow to come down when stopped at lights.Thanks will report back

[PAT303]

Mines was the same.Stop at the lights and it took a second or two for the idle to settle. Pat

[V8Landy]

Disconnected stepper again but the surge is still there?.

[V8Landy]

I think this may be a electrical problem now. Tested the leads with an ohm meter and they varied from 2.6 to 3.5. Since i have had the vehicle(3 yrs) i am on the 4th cap and rotor(this last one original). The plugs and leads are only 6 mths old. I cleaned the metal points inside the cap they were a little black and i cleaned the rotor button. I will throw a set of plugs and leeds at it and see if it fixes it. Otherwise a new cap and rotor unless someone can steer me in the right direction. The coil is putting out a fair bit of spark but i don't know if it is the correct coil. Which coil should i have on it, The one on it now has no readible numbers ect. On the clamp it says Lucas but can't read the numbers.

Any help would be highly appreciated.
Thanks Brett

[V8Landy]

O.K i have replaced the cap rotor leads plugs coil and redid the mixtures. Still have a surge so take it to my local mechanic we are driving along and asks when the snorkel went on. He turned the snorkel head around and the surge stopped turned it to the front again surge returned so point it backwards and all is good(Gee do i feel bloody stupid:p). I will look for a more permanent fix but at least i know the problem now.;)

[V8Landy]

I have now put a balance pipe from the converter to the dirty side of the air box. It has levelled it out but i would expect to still get some surge on a windy day. still it is better than filling the air box up with muddie water.:D

http://img206.imageshack.us/img206/600/balancepipe1wx8.th.jpg (http://img206.imageshack.us/my.php?image=balancepipe1wx8.jpg)http://img249.imageshack.us/img249/2025/balancepipe2kg1.th.jpg (http://img249.imageshack.us/my.php?image=balancepipe2kg1.jpg)

[mike 90 RR]

so take it to my local mechanic we are driving along and asks when the snorkel went on. and all is good

Bit of a cluey mechanic you have got there :)

so what's the theory behind that ... Obviously its getting more air pressure .. but what is it effecting??

Is it affecting the MAF?? ;)


Mike

:)

[stage one]

Yes gas is an amazing system, I don't know a lot about it. I used to work as a taxi mechanic and one of my cars ran on gas, a ford xf wagon. I learnt over my time that a gas system can be tuned one day a stuffed the next! I wish I could quote the terms, but its been a while. most gas systems are set to run rich, so you don't come back every day and complain when the weather changes, beause a convertor is a regulator and reiles on atmospheric pressure to operate correctly. I found I could get amazing ks to the tank by adjusting the mixture and reaction screws to the conditons of the day. This should be easy to do with just your fingers if you convertor is easy to get to. Storms= low pressure, nice day most likely=high. I strongly suggest that you do some reaserch on your convertor, theres a few types, and learn to adjust it yourself. You can't run lean on gas, it just won't go, or will have no power. So there is nothing stopping one from playing with the system. But you can run rich. Once you master the settings on your convertor, you won't need to see a mechanic again, and you will save on gas, you will spend a little more time under the bonnet as the weather changes. Disconnect that balance hose and see what happens.

[V8Landy]

Bit of a cluey mechanic you have got there :)

so what's the theory behind that ... Obviously its getting more air pressure .. but what is it effecting??

Is it affecting the MAF?? ;)


Mike

:)

It affects the diaphram. I don't know exactly what it does but has something to do with it changing from rich to lean with the forced induction. The maf as far as i know isnt used on the gas in this system.
Cheers Brett

[V8Landy]

Yes gas is an amazing system, I don't know a lot about it. I used to work as a taxi mechanic and one of my cars ran on gas, a ford xf wagon. I learnt over my time that a gas system can be tuned one day a stuffed the next! I wish I could quote the terms, but its been a while. most gas systems are set to run rich, so you don't come back every day and complain when the weather changes, beause a convertor is a regulator and reiles on atmospheric pressure to operate correctly. I found I could get amazing ks to the tank by adjusting the mixture and reaction screws to the conditons of the day. This should be easy to do with just your fingers if you convertor is easy to get to. Storms= low pressure, nice day most likely=high. I strongly suggest that you do some reaserch on your convertor, theres a few types, and learn to adjust it yourself. You can't run lean on gas, it just won't go, or will have no power. So there is nothing stopping one from playing with the system. But you can run rich. Once you master the settings on your convertor, you won't need to see a mechanic again, and you will save on gas, you will spend a little more time under the bonnet as the weather changes. Disconnect that balance hose and see what happens.

Yeh the mechanic has showed me how to adjust it so i will play around with it. Might stuff it up but thats part of the fun:p

[Tank]

I would be checking the condition of your air filter, the filter is designed to take air from the front where the trumpet snout was. Your filter would need to be rotated and cleaned regularly as you have the air directed at one small area of the filter. I will try and post a pic of how I changed mine from your setup to breathing as it was designed to, the change made a difference to performance and filters lasted a lot longer, Regards Frank.

https://www.aulro.com/afvb/images/imported/2009/01/391.jpg

[V8Landy]

I would be checking the condition of your air filter, the filter is designed to take air from the front where the trumpet snout was. Your filter would need to be rotated and cleaned regularly as you have the air directed at one small area of the filter. I will try and post a pic of how I changed mine from your setup to breathing as it was designed to, the change made a difference to performance and filters lasted a lot longer, Regards Frank.

Yeh this was a concern but it was the easiest for me with so little room. I have a K&N washable filter installed so rotation and washing will overcome the cons of this set up. I would still like to see some photos of yours to compare as it maybe worth changing it but will wait and see.

[Tank]

If I had LPG like yours I would be getting rid of that enormous Washer Bottle, which would give you plenty of room.
K&N filters will allow up to 38% more particles through compared to the OEM filter. Also the oil medium in the K&N filter can contaminate the Hotwires, I ruined a new engine in 15000klms using a K&N filter which dusted the engine, there is plenty of research available on this Forum which will give you info on these filters, if you go to Gallery and the Albums, Tank, you will see in pics how I did mine, Regards Frank.