Peter Taylor Posted March 13, 2009 Report Share Posted March 13, 2009 I have a G1 running a LS1 The current problem appears on the attached dyno sheet. The first couple of runs were nice and consistent and then the next three runs (attached sheet) the A/F ratio jumps around. This is the 3rd dyno session it has done this although the first 2 the A/F ration jumped around every run. We have hard wired the fuel pump on to make sure there wasnt a voltage issue to the pump but no change. Any ideas as to why the A/F ratio is jumping around would be greatly appreciated. It has a little gold modules for each of the injectors. Any ideas what they are for? CheersDyno-9.march.pdf Quote Link to comment Share on other sites More sharing options...
Cameron Moore Posted March 15, 2009 Report Share Posted March 15, 2009 Hi Peter,The little gold modules are power resistors, they are used to limit the current to low impedance injectors to stop them from burning out.As far as you A/F ratios goes, are you using intake air temp correction? As you do more runs the air in your engine bay gets warmer and you'll get heat soak in your intake manifold. Hotter air means less oxygen, therefore richer A/F. One options is to take a log before and after the changes. If your injector duty cycle is staying the same then it's not the computer and your air density is causing it. If not then the log should show what parameter is changing to cause the A/F change. Feel free to post the logs if the problem is not obvious.-Cameron Quote Link to comment Share on other sites More sharing options...
Peter Taylor Posted March 19, 2009 Author Report Share Posted March 19, 2009 Hi Cameron, Thanks for that. On further investigation their is no IAT sensor, so I wont be able to setup air temp correction until I put a sensor in. It has never had one before. It makes sense though as the second 3 runs on the dyno was after it was just shut off so heat soak would have set in and got progressively leaner as the engine was run and cooled slightly. Although there was quite a big change in AFR. The motor is in a pro buggy so only used for race purposes. It is setup on TPS but only using the first 4 rows on the fuel & ignition charts. Do you think there would be a performance advantage in resetting the TPS to use more of the rows and retuning it to suit? Is it possible to send the tune over for you to have a quick look at to see if there is anything else we are missing? Is that something you do? Thanks Peter Quote Link to comment Share on other sites More sharing options...
Cameron Moore Posted March 19, 2009 Report Share Posted March 19, 2009 Expanding your rows out would mean a re-tune, if that's not an issue then go for it. You'll probably gain a bit more throttle response, and mid range power. But if your buggy spends most of it's time at full throttle then you should be fine as you are. Add that IAT, and you should be good. We can have a look at your MAP and a log if something was wrong, misfire etc, but otherwise there not much we can do. Quote Link to comment Share on other sites More sharing options...
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