injectors not firing under load

s300 and SManager software questions & answers
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royalblind
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Joined: Wed Feb 18, 2015 8:26 pm

injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 10:18 am

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- 1990 CRX, D16a6 (built block and head, stock cam, non-vtec)
- Skunk 2 Pro Series Intake and Throttle Body (IACV, IAT, TPS and MAP mounted to intake in stock location, PCV valve still in place)
- Stock IPT 240cc injectors
- Currently running p28 basemap with vtec disabled (along with some other options off that are not applicable to my setup)
Recently completed all the work on this engine and dropped it back in 100% stock. Ran like a champ, zero issues at all, on the p28 base map mentioned above. I got it 100% setup for boost (all parts installed 1000cc injectors, coolant lines, oil lines, pipes, turbo, etc.. ) and was waiting for time at the dyno to get it tuned. It sat for maybe 3 months while waiting. OF COURSE, my wife got pregnant, so I made the choice to return it back to N/A (removed everything except the intake and throttle body) to save money and time that I will not have due to the new child.

Here is the issue; now that it is back to stock it will start up and run no problem, idles fine and will even rev up (in neutral) without any hesitation. However when as soon as its in gear and i attempt to apply any throttle it immediately go lean (like 16:1 lean) and then a "idle loop" starts, where the engine will rev up and down (over and over again until the engine is off). During this "idle loop" when the idle drops the injectors are @ 0ms however the MAP sensor is still showing a consistent reading and the VAC pressure isn't changing. I would normally assume this is a typical vac leak or air in the coolant but i have checked this multiple times and i know i have no vac leaks and the bleeder nipple for the coolant bleeds coolant as soon as opened.

I am wondering what sensors i can bypass to see if they are affecting the idle; ECT, IAT, ELD? It seems very strange that it runs fine in neutral (even a quick pop of the Throttle Body to wide open sounds clean and smooth). Else i would assume this is a non-s300 related issue.

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Spunkster
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Re: injectors not firing under load

Post by Spunkster » Fri Mar 01, 2019 10:50 am

Make sure you have not swapped the MAP and TPS plugs.

royalblind
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Re: injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 12:32 pm

Had no idea they are interchangeable. Will be checking shortly.

royalblind
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Joined: Wed Feb 18, 2015 8:26 pm

Re: injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 4:20 pm

Not switched, tripled checked and they in the correct places. Map sensor on top of the TB has the disconnect purge solenoid(?) plug. I remove it and the MAP from the firewall when I swapped to the new intake. Never used the purge solenoid for the last 10 years, tank vapors are routed back to the tank via a low pressure return valve (another long story). But its been like that for 10 or so years.
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royalblind
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Joined: Wed Feb 18, 2015 8:26 pm

Re: injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 4:53 pm

This is a snip of the s300 graph as the "loop" is occurring. I knew it was going to happen so i only let it go once or twice because I knew it would not stop, before stopping the engine. MAP is still registering but bellow the normal -17 (+/- 1) that it would idle at.

I dont have a log of trying to drive it but, as soon as anything more than half clutch is applied the engine will start looping like this. I am able to pull it in and out of the garage with out issue but beyond that its like I'm learning to drive a stick.
Image

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Spunkster
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Re: injectors not firing under load

Post by Spunkster » Fri Mar 01, 2019 5:10 pm

Post your calibration and a datalog showing the issue.

royalblind
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Re: injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 8:20 pm

I may have inadvertently found the issue when you mentioned the TPS.I turned the key to the 2nd position and tested the TPS while watching the gauges (s300 mobile) and saw that even with 1/4 throttle open it dint register. at WOT it only registers 60%. Would this cause this type of issues? I haven't had the throttle cable hooked up as I still need to make a bracket for it since its from a '92.
Logs and conf attached
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current_config.skl
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royalblind
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Re: injectors not firing under load

Post by royalblind » Fri Mar 01, 2019 8:21 pm

2-24-19.2.s3d
(859.14 KiB) Downloaded 17 times

crluver123
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Re: injectors not firing under load

Post by crluver123 » Fri Mar 01, 2019 9:47 pm

if it didn't register until 1/4 throttle or higher, and only reads 60% at WOT, then the tps is installed on the TB incorrectly. There is a tang in the tps that needs to go in the center of the two tangs in the TB. You usually need to set the sensor on the TB offset a decent amount for them to line up, then rotate the tps until the screw holes line up. Get that straightened out first. Then calibrate the tps through hondata TPS parameters tab. If there are any issues after that, proceed with further diagnosis based on any new symptoms

royalblind
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Re: injectors not firing under load

Post by royalblind » Sat Mar 02, 2019 4:02 pm

crluver123 you got it man, took the TB off and sat there with "s300 manager" sensors tab open and adjusted the TPS until it showed 0% (with TB closed and) 106% at WOT. If I would have to guess, since i increased to a 70mm TB, the overall circumference of the plate is larger. Since it has to travel a longer distance to reach WOT it reads as 106%.....either way it seems to have no effect on performance.

Car is running great now, just need to tow it to a dyno and have it tuned as its running kinda lean with the larger intake.


NOTE:
For anyone with a d16 and a sunk 2 pro series TB you will need to use a dremel tool to carefully cut flat head threads into the TPS "screws". They are essentially rivets with threads on the stock TB. You will need new screws when re-installing into your new TB. You will also need to go into calibration and make sure that your max voltage is set correctly. From what I have read and found it was (for a 91 crx si) 4.51v. It will not read correctly until you do this. I struggled for an hour before realizing that my calibration had an incorrect voltage setting.

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