Fuel temperature correction

For discussing B&G MS-I/MS-II set-up and tuning of fuel parameters (including idle valves, etc.).
Forum rules
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.

If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.

If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days

The full forum rules are here: Forum Rules, be sure to read them all regularly.
Post Reply
Nick Jones
MegaSquirt Newbie
Posts: 3
Joined: Mon Mar 07, 2005 2:10 pm

Fuel temperature correction

Post by Nick Jones »

Can't find any previous on this one.....

"Does fuel temperature make a significant difference to AFR and is there any existing way in MSII to correct for it?"

Normally resident in cold damp UK and all tuning has been done in those conditions. However, I have done alot of miles in France and Switzerland recently with temperature in the high 20s or low 30s ºC and found that the car was getting significantly better gas mileage, but still running really well. Presumably this means that my basic tune is still a bit richer than it needs to be and something was leaning it a little. Unfortunately no laptop to hand to see what was really going on but I'm guessing that two things could be causing this:

1. IAT was obviously up compared to tuning conditions - I've previously been suspicious that the IAT compensation takes a bit more fuel out than it should but as this has mostly becomes evident at low speed in traffic, I've always blamed heat soak - maybe a bit of both in reality! I know there is a way to compensate for this and will have to experiment.

2. As the fuel re-circulates and the tank is fairly small the fuel was getting properly hot - more than 45ºC. As this will reduce density and pulse width remains the same, less fuel will be injected. As far as I know, there is no way within MS to correct for this - maybe because it is considered un-necessary?

I'd like to reduce fuelling and enjoy the better economy all the time, but I'm also aware that if I do this without considering the above the car may run badly next time I take it somewhere hot......

Incidently, the car has done in excess of 5,500 miles since the beginning of August (2,958 in just 5 days :shock: ) in temperatures up to 34ºC and at altitudes up to 2,500m, without missing a beat - I now consider MS thoroughly tested and it's great! :D

Thanks

Nick


Car is a 1967 Triumph Vitesse 2.0 running multipoint injection on a homemade plenum manifold. Ver 3.0 hardware, MSII processor, 2.89 firmware, MAP algorithm, barometric correction and also controlling ignition via EDIS 6. Big (for Europe) engine in a small car - it gets hot under the bonnet.
Top
tvdl2000
MegaSquirt Newbie
Posts: 8
Joined: Wed Sep 30, 2009 5:42 am

Re: Fuel temperature correction

Post by tvdl2000 »

could you send me your MSQ file.... if testing under that many miles has gone well I wanna use it :P I wil have to mod it but it'll get me closer then i am right now.. won't start....
Top
Post Reply

Return to “Tuning Fuel and Air”