Pembslandy Posted September 9, 2014 Share Posted September 9, 2014 Please excuse this as my first posting on the forum. By way of an introduction my name is Alan from West Wales a Land Rover 90 owner and also technically inept. Last year I bought an ex challenge truck. 1994 Range Rover 3.9 auto running micro squirt. The previous owner had done a couple of comp safari's with it and is tuned in that sort of vane as a 4.6. I use it for trialling and therefore running relatively low speed. The truck ran relatively well albeit going through a lot of plugs and I also changed the MAP sensor and CTS sensor last year. I've competed a couple of times this year but after a lay up of a couple of months it is running like a bag of pooh. To me (and remember the technically inept bit) it is over fuelling to the point that it just pops and "clogs" on acceleration and the amount of petrol fumes coming from the exhaust is enough to make your eyes water. I am thinking that as MS is an electronic ECU, there is no way that the mapping could change on its own (and I haven't messed with it), so I have ordered some new sensors to see if that is a cause (MAP CTS and MAT) I have bought an old laptop and put megatune on it, but I'm really not sure what I am looking at. It was an achievement in itself getting the laptop to talk to the ECU. The only thing I have checked is the coolant temp - and it rises accordingly. All suggestions are welcome and as I said previously, please excuse this as my first post, but it is now driving me to distraction. Regards Alan Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 10, 2014 Share Posted September 10, 2014 Does it have a lambda probe? If not then fit one and you can read the fuel/air mix and tune accordingly Don't discount other issues after being laid up, like sticky injectors... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 10, 2014 Share Posted September 10, 2014 If memory serves, Microsquirt is a bit close to the wire in being able to handle 8 injectors (it's more designed for motorbikes), let's hope it's not a dead driver transistor. Sensors are a quick thing to check via the tuning software - if any of them are giving outlandish readings that's your first thing to investigate. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted September 10, 2014 Author Share Posted September 10, 2014 Thank you for your suggestions. My next chance to look at it will be on the weekend as its at a friends. I am not that offay with mega tune but I assume that if the temperatures rise on the gauges for Coolant and Manifold then the sensors should be ok ? I am loathed to put another set of plugs in (BPR 6ES) as the last lot were sooted within half an hour. I will report back with my findings Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 11, 2014 Share Posted September 11, 2014 Yes, one of the points of MS is that you can plug the laptop in and see what's going on. Sensors generally fail in one of two ways: Open circuit / disconnected, or short-circuit. In either case this usually means the reading is nailed at one extreme of the gauge or the other. If the reading is in the ballpark of "about right" or at least not pegged at the end of the gauge, it's probably OK. Bear in mind MAP will be pegged at about 100 when the engine is off. Also, lambda sensors can get coated in unburnt fuel and read wildly wrong if you run really rich for any length of time, this can then throw the O2 Correction off in the MS as the lambda sensor will read very lean despite running very rich, and the ECU will just keep adding fuel. It's a good idea to limit the O2 correction to a small range so it can't stray too far from the map, and if in doubt turn it off temporarily to avoid confusing the issue. Also check you have MegaTune configured for the correct version of ECU firmware, usually it will throw an error up if it detects the wrong version. As Bowie says, don't discount the more obvious "hardware" issues like stuck injectors / fuel pressure regulators etc. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted September 11, 2014 Author Share Posted September 11, 2014 That's really interesting, I hadn't considered the Lamda previously. But it is a distinct possibility with the amount of unburnt fuel that is being thrown into the exhaust. If I am reading your post correctly above, it is possible to disable O2 correction as a way of testing the lambda ? I really need a few hours of uninterrupted "man time" with my lap top and ECU to try and understand what is going on. Even the interface of megatune scares the heck out of me !! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 11, 2014 Share Posted September 11, 2014 Buy TunerStudio MS, it is a lot nicer to use..... And yes you can disable o2 correction, but that shouldn;t be the cause of running THAT rich.... unless someone has set the authority WAY too high -it should be around 5% Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 12, 2014 Share Posted September 12, 2014 Additionally, the O2 correction should NOT be active around idle or it'll hunt around, the RV8 likes to idle a bit rich. Generally I leave it switched off below 1500rpm ish. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted September 12, 2014 Author Share Posted September 12, 2014 Buy TunerStudio MS, it is a lot nicer to use..... And yes you can disable o2 correction, but that shouldn;t be the cause of running THAT rich.... unless someone has set the authority WAY too high -it should be around 5% Additionally, the O2 correction should NOT be active around idle or it'll hunt around, the RV8 likes to idle a bit rich. Generally I leave it switched off below 1500rpm ish. + Superb info - Thanks. I saw your reply on another thread ref cleaning the Lambda and setting the control authority to about 10%. Hopefully will have a few hours to play tomorrow. Want to change the fuel filter also need to check the MAT sensor. I have it unplugged at the moment, but if memory serves me correctly I was getting a temp reading in megatune when I tried it last week - but I could be wrong as I am as previously said a bit of a technophobe. Will report my findings back. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted September 12, 2014 Author Share Posted September 12, 2014 Further to my previous post, my friend has just rang me. He's been looking underneath this morning and the exhaust pipe and silencer have been pretty much crushed which would of happened on an event previous to the over- fuelling problems occurring. The lambda is 6" in front of this restriction. I'm hoping that this is causing the Lambda to give false readings. In hindsight this could possibly explain the sudden change to running between events. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted September 18, 2014 Author Share Posted September 18, 2014 Sorry not much to report back since last posting. My friend has tested the Lambda and it appears to be kaput. I have ordered a new one plus we are going to be making a new rear exhaust/silencer up as the old one was beyond repair. Hopefully will be fitted next week and I will update when I get some more news. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 18, 2014 Share Posted September 18, 2014 Rule #1 of Megasquirt: It can't fix mechanical problems! Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted October 3, 2014 Author Share Posted October 3, 2014 Hi Just a small update. We have made a new exhaust and fitted a new lambda. Also checked the CTS and MAT sensors which seem ok, also a put a new MAP sensor on. However the problem remains. It starts and ticks over really well and will take gentle acceleration up to around 2600rpm when it then appears to dump fuel in and backfire. We have noticed that the spark at the plug is weak - yellowy orange instead of blue. Next port of call is to swap the coil packs for new. Are we missing something fundamentally simple in addition to what we have already done. Someone has mentioned to check the TPS. Could that be a possible cause? Cheers Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 3, 2014 Share Posted October 3, 2014 It's very helpful with this sort of thing if you can post a data-log file from Megatune / Tunerstudio, that way we can see exactly what's happening. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted October 4, 2014 Author Share Posted October 4, 2014 I thought that I did a data log last weekend, but cannot find it anywhere on my lap top now !! Told you I'm technically inept. I will attempt again. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted January 10, 2015 Author Share Posted January 10, 2015 Hi folks Its been a while since I started this topic but time has been my enemy, plus my lack of knowledge. Hopefully this afternoon I managed to data log what is happening to my engine and with luck post the file here. Would be really grateful if it could be reviewed and explained to me with kid gloves if anything is apparent to my "over fueling" dilemma. Many Thanks Alan datalog201501101348.msl.pdf Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted January 10, 2015 Author Share Posted January 10, 2015 map 10.01.15.msqI don't know if this will help but its a copy of the MAP Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted January 14, 2015 Author Share Posted January 14, 2015 Hi Folks - Has anyone any thoughts on my data log above. Thanks Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 14, 2015 Share Posted January 14, 2015 Not really seeing anything that stands out, except the 255 value in your VE table, but you shouldn't be anywhere near that when the backfire happens (but I'd still get rid of it!). Let's hope someone else can shed some more light on it. Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted January 15, 2015 Author Share Posted January 15, 2015 Thank you elbekko Quote Link to comment Share on other sites More sharing options...
Pembslandy Posted July 20, 2015 Author Share Posted July 20, 2015 It's been a long time since I started this thread - but at long last a few months ago I solved the problem. It was simply a case of the fuel pump being dirty and the injectors not getting enough fuel pressure and therefore staying open and causing the over fueling. I fitted a new HP fuel pump and new filters pre and post the pump and cross everything I have done two events now and everything seems as it should. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 20, 2015 Share Posted July 20, 2015 That's a good result, well done finding it! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 22, 2015 Share Posted July 22, 2015 Excellent, and bonus internet points for logging back in to post the solution! Quote Link to comment Share on other sites More sharing options...
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