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jigga009

Issue with oscillating/bouncing idle when at operating temps

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15 minutes ago, jigga009 said:

Ahh - My mistake.

I will change all the values to 0.7 and try again. Sorry about that. :) 

Just the ones that are currently below 0.7 ;)

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2 minutes ago, ClintBHP said:

Just the ones that are currently below 0.7 ;)

Silly question, but is there a special significance to the value of 0.7 as far as injectors go in general? Or could you have easily told me to use a different deadtime value?

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9 minutes ago, jigga009 said:

Silly question, but is there a special significance to the value of 0.7 as far as injectors go in general? Or could you have easily told me to use a different deadtime value?

I based 0.7 on your original file you uploaded, I just want to get rid of the steps in the table that are making your AFR drop, you will need to trim this depending if it goes rich or lean.

You will probably end up with about 0.1 drop as your cells move right so you could also try 11=7.4 12=7.3 13=7.2 14=7.1 etc as long as you do not have the steps you have now, as soon as your dead times change your AFR is dropping through the floor.

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Clint - took a log at idle with the AC coming in and out, and I think the cooling fans were also coming on and off also.

 

LINKECU FORUM TestMAP - 1.4.pclr

log 1 for testmap 1.4.llg

 

I *think* I was able to do as you asked. I'm not sure I can make sufficient changes to the deadtimes in individual cells in order to bring actual AFR in line with target AFR while still keeping the values of adjacent cells close together in value. I did try to trim the figures as you mentioned though. Please let me know if things are on the right track. 

On other news, it seems that tweaking the deadtimes of the injectors has allowed the oscillating idle to return. Not as bad as before, but it comes and goes. I suspect it might be that the idle lockout isn't high enough... I was going to try playing with it, but only want to make limited changes prior to an expert telling me otherwise :)

 

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Ok that is better the next issue I want to resolve is the Closed Loop Lambda, right now you are not hitting your target AFR and the clamp on the CLL is always at -7% which means you are running rich all the time, approximately 8.2% rich. I would like you to change this from 7% to 15% and report back.

 

Screen Shot 2018-01-25 at 22.56.03.png

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Thanks Clint - I'll carry out the change to the map and report back. You have also reminded me of something with your post with respect to running rich all the time....I think I will also check my base fuel pressure to ensure that it is where it should be.

For a while, I've suspected that the fuel pressure readings I see on my display might have been very slightly (maybe a few psi) higher than I was used to seeing after getting some diagnosis work done on the fuel system prior to the engine refresh. I didn't probe too deeply since the car seemed to drive just fine from the driver's seat, and AFRs did not look far out of the ordinary.  I know the shop adjusted fuel pressure as part of their diagnosis, but I need to ensure that it is back to where it should be. What you are telling me seems to indicate that base fuel pressure might be a little higher than it was when tuned originally. 

It's quite uncanny how just from a few logs you and Adamw are able to tell so much about what is wrong or right on an engine from far away. Meanwhile, I, who drives the thing around had zero idea anything was off!


I'll report back soon.

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Tested the fuel pressure to see what the base pressure was, and what I found was that base pressure was sitting at 50.5psi with the fuel pump turned on and engine off, when it should always have been set at 43.5psi. I promptly dialled it back to 43.8psi (as close as I could get on the regulator without undershooting 43.5psi). Might this explain why the car was running rich as you mentioned? Hopefully this finding doesn't throw all of the idle tuning you and Adamw helped me with into the bin :(

Driving impressions and logs still to come in a few hours. 

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ClintBHP - here is a link to the logs and map:

https://www.dropbox.com/sh/3y3ajrp4tb4zo91/AACxNFy3OBYYi1M75OjnQgwfa?dl=0

With the proper base fuel pressure set, it looks from my layman eyes that the car is behaving better at idle. . I'd love to see what you think.

Log 1 was just with the correct base fuel pressure set.

Log 2 was with the correct base fuel pressure AND expanding he CLL Lambda limit to 15% as you specified.

I experimented with turning on AC on both, but not turning the fans to the max yet.

Thanks again :) 

 

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Not sure.. I suppose it is possible that there could a leak somewhere; I'll have to rent an air compressor to pressurize the intake system and perform a boost leak test in order to confirm.

I do have some non-AVCS high lift long duration cams though, so not sure if that would cause the low vacuum?

I also did not recalibrate the map sensor when I transferred the map over from my V88 to the Link G4+. It wasn't mentioned in the other thread where I was asking about the procedure of making the migration from V88 to G4+. The map sensor settings are identical between both the V88 and the G4+ though when I check the software.

Is there a quick way of knowing whether the map sensor is reading correctly?

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You could check that with the ignition on but the engine not running that MAP = BAP

It looks like when the ECU was mapped you were probably seeing around -50 MGP - Your now averaging -10 - so something is wrong or them cams have a lot of overlap.

If something is wrong you need to fix it,  if its the cams then you will need to switch to a TPS based strategy with MAP compensation, which will require a remap.

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MAP and BAP are reading identically at atmospheric, so I'm guessing it isn't an issue with the map sensor. Nothing much changed in the engine between when it was initially tuned and after the refresh. Went from 99.75mm pistons to 100mm pistons, and a slightly thicker headgasket because some material was skimmed from the block. I just performed a 700km oil change on the engine a few nights ago. 

I'll definitely look into performing a boost leak test on the engine to see if there is an issue there.

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2 hours ago, ClintBHP said:

Ok thats starting to look better, the main issue now seems to be that you have very poor vacuum, do you have a leak, or is the MAP sensor reading incorrectly ?

You, sir, are good!!! Really good!! I found a *very* substantial boost leak in one of the coupler connections. It might as well have been a barn door sized leak.  The person who dropped the engine back in did not tighten a couple of the clamps on the FMIC leading to the throttle body hard enough, and you could literally hear the air rushing out from the connection as soon as I connected the compressor to the charge piping. In fact, the leak was so great that the compressor was unable to put much pressure into the system initially. I did not need soapy water to find the leak. I could hear the low frequency rush of air clear as day. Clamps have been tightened and boost leak tested up to about 30psi, so I think I should be good for what the car was originally tuned for. 

I'll take some logs a little later once I have the intake plumbing back together again. Need to get the compressor back to the hardware store ASAP to minimize renting fees :D 

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You are sill only pulling -10 to -20 vacuum, I would be expecting -50 you sure there is no leak after the butterfly? or the cams are timed correctly and do not have too much overlap.

I idle speed is steadier, it seems its the idle ignition its responding to, I would pull some degrees out the idle ignition map on every site below 0, so -100 would be 6, -200 2, -300 -2,  -400 -6 and -500 -10 keep the old settings as I am sure you still have a vacuum issue.

 

 

Screen Shot 2018-01-27 at 08.44.47.png

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14 hours ago, ClintBHP said:

You are sill only pulling -10 to -20 vacuum, I would be expecting -50 you sure there is no leak after the butterfly? or the cams are timed correctly and do not have too much overlap.

I idle speed is steadier, it seems its the idle ignition its responding to, I would pull some degrees out the idle ignition map on every site below 0, so -100 would be 6, -200 2, -300 -2,  -400 -6 and -500 -10 keep the old settings as I am sure you still have a vacuum issue.

 

 

Screen Shot 2018-01-27 at 08.44.47.png

ClintBHP - Thanks for the response! Yes, definitely zero leaks now. I had the entire engine bay sprayed down with soapy water looking for bubbles while the intake system was pressurized to over 25psi :) 

I was actually curious as to whether the amount of vacuum the engine has differed to what it had when it underwent its first refresh a few years ago by another specialist racing team, so I had a look at some old videos I have of my gauge readouts after the first refresh that I keep in order to give me some perspective on what the readings look like on Day 1, and it was drawing the same level of vacuum as is now. The previous refresh and this refresh it just underwent were performed by different specialists, yet the vacuum at idle is the same on both occasions years apart. The cams in the engine are a lot more of a drag-spec application than they are for street use, as the engine is fed by a "large frame" turbo.

I will make the changes to the map, and report back! 

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2 minutes ago, neil brown said:

did you calibrate the map sensor using the drop down menu

Yes, map sensor was calibrated via the drop down menu. It was within spec all along. I did have a pretty large boost leak in one of my intercooler pipes that i fixed, and confirmed that the system integrity by watching it hold pressure for close to a minute. The engine has always had the same relatively low level of vacuum while running, even when torn down and refreshed by 2 different specialists over the years. I think it is a function of the drag spec cams and headwork the engine has.

 

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So whoever mapped this almost certainly used a map from a car that idled at -55 

can you change the axis on the fuel map as per this attached picture and report back:

 

Screen Shot 2018-01-27 at 19.53.25.png

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Take this is a Subaru 

 

on mines it idles at 900 rpm with -70 vacuum on the gauge with a Garrett gt2860rs turbo running a g4 storm wire in unit 

 

are the cams set up correctly

tpo much over lap or map sensor tubing wrong hole on inlet or is it shared like off a t- piece on another vac line

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53 minutes ago, neil brown said:

Take this is a Subaru 

 

on mines it idles at 900 rpm with -70 vacuum on the gauge with a Garrett gt2860rs turbo running a g4 storm wire in unit 

 

are the cams set up correctly

tpo much over lap or map sensor tubing wrong hole on inlet or is it shared like off a t- piece on another vac line

Yes, cams are set up properly. They are just a lot more radical than what people normally run on the street, and the vacuum at idle is telling. We found out years ago that connecting the map sensor directly to the intake manifold on this engine setup resulted a very turbulent map signal. A short section of vacuum hose had to be used to get a more stable signal. It does share a vacuum source with the Aeromotive fuel pressure regulator. As mentioned earlier though, there are no leaks in the system.

After doing some digging into other setups running similarly radical cams (i.e. the specialist's shop car's race engine) the vacuum readings appear to be right in line. It is also in line with what it produced on its first refresh by a different specialist shop.

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My map sensor is connected directly to intake and is in stock location but it’s a gm 3 bar unit and have not issues with it

have you done a smoke test on the inlet manifold will tell you if manifold to head gaskets are leaking or leak on the inlet itself

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14 hours ago, neil brown said:

My map sensor is connected directly to intake and is in stock location but it’s a gm 3 bar unit and have not issues with it

have you done a smoke test on the inlet manifold will tell you if manifold to head gaskets are leaking or leak on the inlet itself

Map sensor works fine, as we tried it on other cars, but the cams in this engine in particular are such that they cause the map signal to bounce about a lot when the sensor is directly bolted on.

No smoke test this time... I have done these in the past, but my issue with them is that unless you have the ability to pressurize the plumbing, you don't see any leaks unless they are gaping leaks that you can drive a car through. I find that using pressure test works better with soapy water, as I can hold a certain PSI in the system using an air compressor (e.g. 25psi), and then spray soapy water at all vacuum hoses, intercooler couplers, joints - basically anywhere air could possibly be leaking between the turbo compressor outlet and the heads of the engine, and look for bubbles to start growing in areas where there are leaks. I have found this to be a reliable method for checking for boost leaks in the plumbing, especially up to the boost pressure that the plumbing will see at full boost. Sadly, it involves renting a decent size air compressor from the hardware store, but it is worth it imo.

On 1/27/2018 at 2:54 PM, ClintBHP said:

So whoever mapped this almost certainly used a map from a car that idled at -55 

can you change the axis on the fuel map as per this attached picture and report back:

 

Screen Shot 2018-01-27 at 19.53.25.png

ClintBHP - Performed the changes you mentioned, and took a log:

I did notice that since correcting the base fuel pressure and making the changes to the closed loop lambda fuel trim limits you mentioned, the ECU will always trim the AFR's back to around target whenever I turn stuff on. Glad to see that happening :)

https://www.dropbox.com/sh/oz34qbcovkx0jk7/AAAElv6xBm6QmXvw9jVO48Gxa?dl=0

 

Please let me know what you think :)

 

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