Lowest price on EBay for Siemens. $150 for set of 8
https://www.ebay.com/itm/35432081765...temCondition=3

 

I thought so as well, but it fails emissions during acceleration. If I wasn't at 5500ft, I would just throw in ev6 bosch replacements. Oil pump and timing chain is new <200mi. Sensors in range for O2, temp, manifold and throttle. Fuel pressure at 38psi. Compression is 165psi. Everything looks good. Fuel rail bleed down is about 15secs, not so good.

I could have bad oil rings or leaking stem seals, but it would show up on idle, I don't blow black smoke on start or burn a quart of oil every 200 mi.. The injectors look like the culprit and easiest fix. I don't want to start throwing parts at it. I lived that with an old Jag and a couple MGs. I ended up getting the wrong timing advance springs, not good. If I'm going to throw $$ I don't want to waste them with trial and error then still fail emissions

I'm almost done with figuring out the right flow rate for substitute injectors. I thought ( I was told) speed of the injectors played a "big roll" in selection, well maybe it did 30 years ago. All modern injectors open and close fast (0.5 ms to 1.0ms), so injector speed is not an issue. With the stock ecu and at idle, injectors fire between 3ms-10ms depending on temps, rpm and AC on/off. Fully open @5500 rpm, injectors are on for 70ms-80ms, depending on temps and rpm.

Bottom line: It all comes down to flow rates for a given fuel pressure and impedance match so you don't burn out the ecu.

At least I feel like I almost know what I'm talking about now. Maybe documenting it here will help others in the future.

 

How old are you O2 sensors? And if you replaced them, what brand did you put in? O2's can *look* like they are doing their job, but, that does NOT imply they are accurate..... and the PCM has no way of knowing the data it is getting from them is just wrong...... Of course, in open loop, O2 sensors are irrelevant. So, depends on how hard you are accelerating if the sensors matter or not.....

I understand where you are coming from, and now understand why you are diving down this particular rabbit hole. But, keep in mind, flow vs pulse width vs fuel pressure is NOT linear, and not every manufacturer rates their injectors the same way...... and that REALLY complicates things.

 

Buy a stock set of injectors and copper plugs. You keep beating around the bush. You can get a matched set of rebuilt injectors and can be within 5% between all 8. You are trying to reinvent what people have done already. Mr Injector or Injector Experts (just a couple off the internet) will take your injectors and clean, rebuild and test (or just buy a set from them). Email/contact them with what you want to do and they will provide a proper injector. Sorry this sounds gruff.

 

Thanks for replying... I only use OEM parts if I can get them. The O2 sensors were replaced about 7 years/50K mi ago. I used mopar Mopar 56028301, part number from the fsm. I bought 4 NOS in 2010ish.

I pass emissions idling and cruising. Accel and decel is the problem. I'm trying to get an emissions waiver because most parts are unavailable. I tried to change my registration to a farm vehicle, but needed to prove I own a farm which I don't.

 

Not sounding gruff to me. I did get them rebuilt 3-4 years back and they still leak only worse now. Back then, the rebuilder said 5 of them are "crap". Most rebuilders are moding injectors for performance ei 500hp+ and I'm not spending $1,000 on injectors. I'll get an off-the-shelf part. The way forward is to 1) understand the problem, 2) collect the relevant data and 3) find one or more new, commercially available substitutes with a warranty.

Some of the solutions may work at lower altitudes. My truck normally operates between 5500 and 7900 ft altitude,, that is 18%-25% less fuel running open loop which is most the driving in the mountains. The fsm and @Hey You says the pcm/ecu open loop mode already runs rich at sea level, it's likely overly rich at altitude. Since I moved here, my mileage has been between 12-6 mpg with low power. In retrospect, my 1st cat likely died because of the overly rich fuel mixture.

Back in the day, we needed to swap carb jets for altitude. On this pcm/ecu and mountain roads I need to swap injectors or change the fuel pressure. Either way, the calculations for the right injectors need to be done.

 

PCM bases its fuel shots on several sensors, engine temp, throttle position, and MAP. (manifold absolute pressure) So, the PCM already knows to compensate for altitude. If you have injectors that are leaking, then some simple stock replacements should solve the issue for you. *should*

Mopar part number I come up with is 53030262. I can't find any of them new... they are all remans. Ebay has a set of flow matched injectors for under 200 bucks.

 

Since I've already gone down this rabbit hole in far too much detail, I'm writing an excel spreadsheet to help with injector selections. I only have bosch tables, to select from, but it's a good start for someone to expand. At least the learning won't go to waste and others can use it.

BTW, the hardest part is calculating BSFC and manifold temp. No readings on OBD1 pcm.

I've ordered the reman off ebay.

 

Intake air temp should be there on OBDI...... May just be called something odd.

BSCF though, yeah, probably going to have to calculate that.

 

Rebuilt injectors are in.. Fuel pressure bleed down is nor in minute vs seconds.. Gas heater for the garage is not turning on, and it's 25 degrees in there right now. I'll finish up after I fix the heater.