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Ryan Simmons

Cold enrichment problems!

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Hi, i own a Linkplus g3 and am using it on a 2.139 stroked 4-cyl 3s-gte turbocharged engine. I am having some quite bad issues at the moment during cold start / warm up. Basically, when firing the engine up from cold, literally after a few minute the plugs have become so thick with black soot from too much fuel that they start to misfire quite bad and does not improve when the engine reaches operating temp. Also i cannot get the idle to stay steady, its always bouncing around from 800 ~ 1200 rpm (idle is set at 1000rpm roughly). I do not know that much about actually tuning ecu's but if there is any information/data you wish me to supply, i am sure i can help. I am running 1200cc injectors, 35psi base idle FP and a Link 7bar map sensor. Cyl compression is good and consistent throughout all cyls. Then when we tried leaning out the warm-up enrichment the idle got much worse and the engine cut out. I also noticed that my TPS reading was jumping from 0~15% every now and then, perhaps this could be the cause? I disassembled the TPS to find it was full of water and muck, so i cleaned it out and it appears to be working better now, however i still have the misfiring. Can anyone help?! Many thanks Ryan

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Thanks martin, i will load it up tomorrow morning and give it a try. Did you find anything wrong with my settings at all? or is that hard to tell without seeing the AFR's etc? Just out of interest, how would the 3d table work different to the table i already had? Also, just noticed something else. On my ecu settings, i have 'AN TEMP 2 - Inlet air temp' : Temp channel #2 : [intake air temp] Temp sensor type: [std bosch NTC] ' I assume the obvious and say this is referring to the intake temp sensor thats located at the air filter? Well i do not have this sensor connected so should this setting be turned off? Or perhaps better still should i re-connect it? Thanks for the help.

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Ok, update! I cleaned the plugs up with a little bit of superfine 1500 grit sandpaper, uploaded the new map and tried it. Straight away the idle is much much better! however when it was stone cold, it was a bit hesitant when you touch the throttle. it tended to want to drop a couple of revs before revving Up. Also when you do rev it, when the revs come back down they tend to drop down to about 600 rpm the back up to idle. I am still getting a misfire, particularly at about 2,500 ish, and got one almighty 'Boom' when i revved it right up once; but i am thinking this could be because the plugs are damaged from carbon build up. The plugs are only 2 days old but it seems it only takes 1/2 hour to turn them jet black and i think they are probably no good after that. Also, like i mentioned in the prev post, shall i re-connect the IAT sensor? or just turn it off on the ecu? Btw, i could do a log, i know how to record and save them but what do i do, ie do i start it cold and leave it record a log without touching it for 5 min? or shall i give it a few revs here and there? thanks

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Hi Ryan.

Although you could get away without an IAT sensor, it is highly recommended that you use one.  Especially if you are tuning things on the edge to get the most out of your engine. 

The last thing you need is to have your engine tuned to it's limits on a hot day, and then take it out for a hard drive on a cold day where the ECU isn't aware it should be dumping in more fuel to allow for the more dense air. 

Of course a wideband could assist with this, but for the sake of under $100, I would just do it.  In saying this, do not use the one in your air filter box as this is pre-charged air and will give the ECU an inaccurate idea of the actual temperature used by the engine (the net result of this would be too rich again).

In the mean time, just check your IAT fuel correction is turned to 'OFF' if you are not inputting an IAT signal.  The input for this temp channel may have a fault value it's reading and in turn this will have an effect on the fueling.

Do the log while it sits there and idles if your going to do one.

Jurgen

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Hi jurgen, thanks for your reply. I realised last night that i may be causing some confusion with my reference to the IAT sensor. I actually have 2 IAT's, one is a Bosch part that is screwed into the intake plenum -this is the one we record the IAT's from when tuning. The one i was referring to was the second IAT which is a small plastic probe thats fitted at the air filter. This is the one that i have removed as i found the connecting wires to be broken and assumed it had been like this for a while. I have cleaned my plugs off and will reconnect this sensor then give the car another go and make a log file. Just a thought, would a faulty lambda sensor thats giving a Lean or No signal when on cold start cause over fuelling? I did notice that pulling the plug on the lambda while the engine was at idle made no difference to the engien revs/operation whatsoever. However im quite sure the Lambda only operates when the engine is at normal operating temp,does it not? thanks

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update... I have cleaned up the plugs and refitted the air filter intake sensor. car fired up and idle'd nicely almost all the way through warmup. Just before it had reached Zero warmup enrichment, it went through a idle hunting phase of about +- 200 rpm but then at 80c it stopped doing it. I logged this and did not touch the throttle. I then did a second log with some throttle blips. I noticed that when i lightly touch the throttle, the revs drop before increasing. The other thing that i noticed (actually i noticed this a while ago but forgot to mention it) Is that if i hold the throttle steady at around 2400rpm, something odd happens. the revs will continuously drop down to 1900 then shoot back up to 2400...almost as if the fuel is cut every time the rpm is 2400 and comes back on at 1900. it doesn't do this at any other revs. Also, when the engine is warm, Lambda is still OFF. on revs, overrun, idle. I will attach the cold start LOG first... (please note, this is the best its run in awhile!)

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and heres a quick log showing the revs between 1900 ~ 2500. note i was just holding the throttle open enough to make 2500 revs and holding it there, it was revving up and down by its self. Sorry the first was in a ZIP file, the log file was larger than the 1000kb aloud limit.

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firstly your log shows clearly that your hitting decel fuel cut...

the secondary iat is not worth using..

plus you could benefit from a fast response type (Wells 109) (Aem type) sensor in your iat..

3d warm up map means you can adjust af for all condtions..

ill chuck you another map together to get the decel fc correct and the warm up fuelling better..

 

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your log shows no change in TPS for when your hitting decel fuel cut.. you need to span TPS correctly.

options, TPS setup.

 

warm up altered to give more enrichement for light throttle... (that is once youve actuall spanned TPS correctly!!!!)

 

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Thanks loads for you help martin. I will upload the new map tomorrow and see how it goes. Btw, will your modified map be fine for full time use? or will i need a remap with AFR gauge? Could you explain what you mean by decel fuel cut? I know what typical fuel cut is, as used as a safety feature, but didn't know it could happen on deceleration? I thought the injectors are usually switched off on overrun/ decel? Also, by 'span the TPS' i assume you mean calibrate? as i have done this procedure quite a few times. iirc the screen tells you to fully press the throttle, click ok, then fully release the throttle and click ok. I did this right before i made that log and from what i could see,it was working fine. 0% while closed, 100% when fully open and the value seemed to increase/decrease smoothly with pedal movement??

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i have only modified the cold start map..

it shows from your log changes in MAP so there must have been a throttle input..

decel fuel cut = overrun fuel cut... cuts gas on engine run down with throttle shut.. for economy and CAT saving.

you need to check that the tps value change the instant you open the throttle or the ecu has no clue what your doing...

i'll recheck the logs for TP voltage to see if that is changing... if it is then i suggests a tps cal problem.. if its not it shows your tps is incorrectly adjusted or faulty

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I checked you map. turn off "overrun fuel cut". There is other settings to change when overrun is enabled. first try when it turned off. In "idle speed control" you have "open loop" in this option ecu doesn't use lambda.Turn it to "closed loop". In fuel setting put "closed loop lambda" to "stoich mode".

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well, i have had success! the problem is now fixed, turns out the problem was mechanical, i had forgotten to thoroughly clean my new fuel system parts and as a result, all my injector intake feeds had gotten clogged up with fluf! this blockage must have been gradually worsening as the car was infact running very lean on idle. god knows why the plugs were going black though? the tps is functioning correctly, dont know why the log file wasn't recording it? we spanned it many times and its working well. quick question while im here, i am going to get my tuning guy to get rid of the idle control valve, he mentioned breifly that all hes gotta do is adjust the idle stop screw and change the ignition advance for the idle? well i am just curious as to how it works? could someone explain it to me in a little more depth? many thanks for all the help :D

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You can to some extent trim the idle speed using ignition.

You will most often use a second table based off TPS. If engine speed falls the ignition timing is increased if it gets too high the timing is reduced.

What are the reasons for removing the idle control valve?

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Well its mainly because the ICV used to be a part of the stock TB and now i am using an aftermarket TB i have had to improvise, making up a plate and pipework for the ICV. it works but it could be better as my revs dip quite low on decel from time to time and it generally looks messy. I am also trying to get a minimalist engine bay and removing the ICV would make a good difference. Is controlling the idle by ignition / TB stop screw not a good idea then?

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