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missfire coming off idle and at high RPM's


Geesel.260z

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Hi guys,

I've been trying to get my car back on the road and I think I'm down to my last issue but can't figure out what the problem is, if you look at the attached graph you can see what is happening. now for the list of what I have checked:burnout: fuel pressure holds steady at about 42psi, added an extra ground wire to all my sensors and ecu directly to the negative side of the battery. I'm not very good with the electrical side of things so any suggestions are welcome :burnout:

 

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no graph attached....

 

off hand from your description though, and assuming that you do not have a wideband gauge since you make no mention of AFR's...

 

i would say you need to work on your tip in response in the acceleration wizard menu, and that you need to add some fuel up top or look at your engine timing.

 

take the car out, in 3rd or 4th gear run it to redline in an area that is dead straight with lots of room, as much as i hate to say this, just after you hit redline clutch in, go to neutral, and shut the motor off... coasting to a stop (again LOTS of room since you'll lose power brakes). Once you come to a stop, pull your plugs and check the coloring, if any of them are white then your running lean up top.

 

the smartest thing to do would be outfit the car with a wideband air fuel gauge though, and i mean a real one, not that $60 autometer air/fuel gauge special.

 

go pick up a AEM UEGO, Innovative LC-1, Innovative LM-1, PLX, etc...

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Need more information about the engine, modifications, etc. in order to better help you. Please post your VE and AFR tables as well.

 

Also, you say high RPM yet your RPMs only go up to 3640.

 

Finally, I *think* I may see the problem. Your PW goes from a minimum of 2 ms to a maximum of 18 ms, yet your MAP stays fairly constant and only increases slightly. A PW of 18 ms is quite high for only 132 kPa. For example, I have a L28ET with 440 cc/min injectors. At 15 psi (~200 kPa) my PW is around 15 ms.

 

What do you mean fuel pressure holds steady at 42 psi? At idle? If so that is too high as it is vacuum referenced. Again, knowing your engine and modifications helps.

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If you look closely at the screen shot you will see that all my sensors freak out at the same time(note the AFR on the below shot as I don't even have that hooked up yet). I'm not sure it will help but here are the tables I'm using and I have a wideband o2 sensor on the way. engine is a stock 82' l28et with a 60mm throttle body. everything else on the engine is stock. As for my fuel pressure I will have to do a little more work on that as it is at 42psi during idle and boost.(stock pressure regulator less than a year old). Oh and as for the RPM's I guess I baby it a bit as I just got it rebuilt ;)

 

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Post up screens of your timing maps (assuming your running spark as well), in the mean time, rescale your maps to somthing like this, and turn off AFR targeting for right now until you have your maps roughed in closer, it will keep the software from making huge changes to a bad map.

 

I did this map on the following assumptions:

1. that you stick to the boost you said you would, the map is scaled for up to 24psi of boost, but it will be up to you to limit it to the boost you stated, i just left you room to grow.

2. that your motor is 100% stock down to the injectors, i used my own base map which runs 440cc injectors, then scaled it up to account for the 370cc injectors you should be running.

3. that this map is mearly to confrim that everything else is functioning properly and that it was a improperly scaled map causing your problem.

 

My personal suggestions are:

DO NOT run this map before posting up your timing tables

DO NOT run this map before installing your wideband 02 sensor and having it ready and interfaced with megasquirt so you can see whats happening

DO NOT consider this map a base map that is safe to go run around with and hunt for civics, as you still have not shown enough about how your car is setup, it is mearly here to see if scaling was your problem.

 

test_map.JPG

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alright, so I got my wideband o2 sensor today and got it installed, I updated all my maps to reflect the maximum of 240kpa, and am including a screenshot of my ignition map. I also was looking at what KTM had to say about my pulse width and wanted to have you guys look at my injector settings because they don't seem to match what is listed in the sticky for my stock injectors. Thanks for all the help :)

 

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alright, so I got my wideband o2 sensor today and got it installed, I updated all my maps to reflect the maximum of 240kpa, and am including a screenshot of my ignition map. I also was looking at what KTM had to say about my pulse width and wanted to have you guys look at my injector settings because they don't seem to match what is listed in the sticky for my stock injectors. Thanks for all the help :)

 

DO NOT run that spark map, plug in these values and it should get you started. Get your wideband hooked up, and go out driving with a laptop, feel your way into the boost and see where the AFR's are at, if you can manage a clean 2nd, 3rd, or 4th gear pull to your redline without the AFR's crossing 11.5:1 under boost then your doing good.

 

Use the MSnS's ability to datalog, record the pulls you do, then pull over and look them over in megalogviewer to make changes, alot safer than trying to adjust maps in megasquirt while driving.

 

Spark2.jpg

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Alright so I finally got to test the settings you gave me and with the VE settings inputted the car wouldn't even idle let alone drive :( is there a book that you can recommend on how to adjust the settings? I have a club dyno day this saturday so I really need to get this thing running fairly good before then...

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36 degrees of timing at 240 kPa? :shock: That other timing table will be a lot safer.

 

There's a pretty good basic tuning guide for the MS at this link:

 

http://www.megamanual.com/ms2/tune.htm

 

You may also want to go over the MS1/Extra tuning manual. It has some other useful tips not in the main one, just keep in mind that it's software specific and several of the settings do not apply to MS2 which you appear to be running.

 

http://www.msextra.com/manuals/MS_Extra_Tuning_Manual.htm

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