PROBLEM SOLVED. IT WAS THE INJECTORS.


Since the weather has been getting really hot here I'm having a problem with my car running lean only after I've been driving for a while and everything is really heat soaked under the hood (90+ degree weather). When it happens it's like a switch is turned on and my afrs go way lean like 17.5-1 and or not even registering on my AEM wideband. I have my afrs tuned for 15-1 cruising and idle, gradually richen it up to 12.2-1 at boost transition, 11.8-11.5-1 in boost. When this problem is happening it's more like 17.5-1 idle and cruising, 14-1 at boost transition, and 13s up until about 7psi after that it dips down on target.

Here are a few pic comparing 2 different logs. I tried to make the conditions the same for both. It was 102 degrees today. The first log is just after getting it to operating temp and the second is after it has heat soaked and started running like dog ****. The iat are basically the same as well as the injector duty cycle. The only difference is one log is much leaner. All other sensors are reading normal in both logs. No cel or weird readings from sensors.

On target no problem



Way too lean, obviously a problem



Same log as first pic, on target



Same log as second pic, starting to richen up. Still too lean though.



I think this is a mechanical problem and not a tuning problem. You can see from the logs the iat is basically the same so I'm sure it's not my iat compensation tables. Im wondering if my injectors are getting heat soaked and not opening as much as they should when at lower duty cycle greatly affecting my afr at lower loads.

I came across this page when searching this issue. Only thing is my problem doesn't go away until the car has cooled down for a while.

M54 Megasquirt 3: Fuel Injector Heat soak

I'm thinking my problem is probably my fuel injectors. I should mention my iat sensor is mounted in my charge piping about 12" before my throttle body for more accurate iat compensation tuning.

my setup basically a stock 1.8 ls engine with basic turbo setup.
Tuned by me on Neptune rtp with demon 2
Osidetiger 600cc bosch saturated injectors (I think that's my problem?)
Stock fpr (I swapped on my AEM fpr, did not fix problem)
AEM 320plh fuel pump (hard wired to battery with relay)
Hondata thermal intake manifold gasket
Coolant temps never go higher then 195*

Let me know if you guys need any more info on my setup. Any help is greatly appreciated as this is a really weird issue.

 

I don't think its heat soaked your iat is all within a few degrees and only in the 110's. now if your iat was 150 thas some heatsoak

 

IATs and under hood temps are different things though. I know under hood temps do generally cause higher iats but he said he's pulling the temp farther up that the stock location on the manifold. I don't know how big of an impact that makes but who knows

 

Post ur iat correction table

 

Very high possibility the injectors are the issue. They have been known to have issues anyways. The problem is you have a relocated IAT. This is good for more on point IAT accuracy, but the injectors are still in the same spot soaking up the heat which would have been shown by a manifold mounted IAT sensor. IMO the IAT Correction Tables don't really matter since the IAT is practically reading the same thing. You can't compensate for a problem with the same readings.

If it can easily be done, I would move the IAT back to the manifold and see if you can correct from there with IAT corrections. If you can, get some quality injectors. I personally only run Injector Dynamics, but InjectorNation would be a cheaper similar alternative.

 

Here is a pic of my iat correction table. These settings get the afrs where I want them until this issue starts happening. It take a while for it start acting up. I've had my iat up in the 120s with afrs on target, then once it starts running like **** I won't stop until the car is parked and cools off for an extended period of time. I've also had the iats in the 90s with it running like **** after driving for a while. I don't think it is a iat correction problem. I think it's the injectors getting heat soaked and not opening enough to deliver the right amount of fuel at lower loads. Anyone heard of that before? I'm not sure what else would cause this.

Iat temp sensor is mounts in the charge piping about 12" before the throttle body.

 

Read my post from above yours. Yes, I have heard of those injectors doing something similar.

 

IN900 Bosch EV14 Fuel Injector Set Honda OBD0 OBD1 B18 D16 H22 F22 - Injector Nation

These injectors look pretty legit. They are having a 20% off sale hmmm...

I have read that these newer style plastic body injectors do not suffer from heat soak nearly as much as the older metal body style injectors.

 

Yeah sorry you posted that while I was making that post so I didn't see it. Thanks for mentioning injector nation as an option. I never heard of them before, but they look pretty legit.

 

Assuming the injectors are heat soaking what I would do is when the car is acting up check the resistance across the coil.

If the reistance is a lot higher then yes that is the problem.

Thermal break down is a real thing.

I would never just swap out parts because internet tells me to.

 

I actually already did that test. My injectors are rated 11.9 ohms and that's what they read when cold, when really hot while this problem is happening I'm getting upper 12s in resistance. So there is an increase in resistance with heat soak, but I wasn't sure if it was enough to cause my problem. I really am starting to think this is my problem though.

 

No thats not enough at all


I would say look elsewhere
On another note, member that dummy shodan saying widebands arent needed? Yeah me too

 

I never said he needed to swap out parts. I suggested moving the IAT as a trial to determine if it was injectors. Those injectors are usually junk. I have owned a few sets myself not knowing any better...

 

Well in all honesty the resistance test probably needs to be done again with a more accurate ohm meter. I was using a shitty hf meter and was getting readings all over the place, but it was clear that the resistance was more on a hot injector.

 

Howabout fuel pressure?

 

I swapped my AEM fpr on and still had the problem. I don't have a fuel pressure gauge. I don't think it fuel pressure though, because afrs dip back down on target after about 8psi all the way to target witch is about 16psi. Same thing with both stock and AEM fpr.

 

How old is the fuel pump.

List off your whole fuel system and how old the parts are

What injectors are you using? I think i missed it

 

Here is a link to my exact injectors.

http://m.ebay.com/itm/201364863919?nav=SEARCH
Fuel setup
AEM 320lph fuel pump (hard wired to battery with relay) brand new
Osidetiger 600cc Bosch injectors 1 year old
Oem fpr
Oem fuel rail
Oem fuel lines
Newer fuel filter

 

I run those injectors. Work really good, never had a problem

 

Could always try stock injectors and see in part throttle / real low boost. I have about 4 sets I could send you if you need it.

 

That's a damn good idea! I think I have 3 sets myself lol. I'm gonna give it a try. I just made a base map with stock injector settings, and boost cut at 1.9 psi. I wont have a chance to test it until later today, but I'll let you know how it goes.

 

I would never just swap out parts because internet tells me to.

 

^^^ lol. I just dug through my old **** and found 2 sets of old injectors, but they are obd0 low ohm injectors and look dirty as ****. Not gonna swap those in. I don't want to wire in resistors just to test this as it would be a bitch with my wire tuck and all. I might just buy the injector nation 900cc injectors lol.

 

Youre assuming ALL your injectors are failing at the same time from what exactly?

Heat soak? The injector is simply a solenoid. If you had high resistance across the coil then yes it would make sense to swap them. Youre injectors dont tho based off your information.

Swapping them is going to waste your time.

Do you have a full tank of gas ? Check voltage at the fuel pump under load

 

Yes I do think it's the injectors. The resistance did increase when they were hot, but like I said I need a better ohm meter to tell exactly how much as my readings were all over the place but higher then when cold.

Yes full tank of gas. Not sure how I would measure voltage at the pump under load? Voltage in logs reads good. If the voltage to the pump was low then why would my afrs dip back on target after 8psi? It seems after about 30% duty cycle afrs go back on target. Honestly these injectors have been pretty inconsistent since day one. I have spend a lot of hours tuning iat compensations and these injectors seem to always be on the rich side when cold and the lean side when hot, only since the really hot weather has it gotten really bad.

Not sure what else would cause this other then the injectors? The rest of the fuel system is solid. My opinion is its the injectors getting hot and not opening enough at lower duty cycles, but that's just my opinion. I started this thread to get the opinions of others too.