Oldblue

Mileage can be effected by tire size, gear ratio dirty throttle body and several other factors.

donbrew

Pumps measure volume, cars measure metered air flow through the throttle body. You get more for your money with cold gas vs warm gas. Some states require a compensator in the calibration.

The cars computer should be accurate to the fraction of an oz. It knows for sure exactly how much gasoline is used by calculating the A/F. If it uses 14.7 Kg of air it uses 1Kg of fuel. That is why the intake and ambient air temp is important. Volume changes with temperature and pressure; a Kg is a Kg.

Rocket Surgeon!

Thank you, This is all good information, but I already know it well. It would be good for others to understand.


In my expeditionary trips (ie junkyard crawls) I found cars that actually had the wrong injectors installed:

Example 1: 06 HHR with 12571863 a 21lb injector, which is an 02-05 ecotech with an earlier type plug connector. Here is how that is possible:
https://www.j-body.org/forums/read.php?f=2&t=468303&a=1
The 02-05 and 06-08 harness can be swapped, as they are basically plug and play with only different injector connectors and same MAP sensor connector.
Maybe a replacement engine, or maybe just injectors and harness, as the injectors were "lately installed" meaning not coked in place.

Example 2: 07 HHR that had an apparent engine with the 09-11 injectors, engine had incorrect brackets indicating it was probably a later engine from another model swapped in.

I doubt either of these cars was properly fixed with tuning, but they may have run well enough with the wrong parts to be functional. It pretty popular for buy here pay here and shade tree mechanics to make something go well enough, even if not right. Many the stories I have seen...

And as for all the 06-07 cars with the stock 12582704 injectors I suspect of being bad design? They look untouched since factory. I would not doubt that they might have run but were stuck throwing P1174 or misfire codes. In some places a check engine light condemns a car to being unregisterable. Most of those cars looked very clean.

An incorrect set of injectors that are an improper flow rate might be okay for the car to run, but they might be beyond the PCMs ability to adjust to lean or enrich. Too far off spec and damage could occur, from too lean burn, to crosshatch cylinder wear and oil dillution. It also would interfere with cluster fuel consumption info which I prefer be correct.

Side note: I have owned two cars where it was discovered that mixed injectors had been installed, and subsequent replacement with a numbers matching set did make those cars run smoother. Just in case you never thought that someone might do that.... A set of injectors that have mixed rates would make the engine a bit rougher, and some cylinders would be running lean while others run rich. That could be bad.

Sometimes I hear the "I need a larger injector for more power" idea. This would be true if you are modding a car beyond the range of your current injectors, but you would need to be able to tune to have the PCM operate them properly. Simply throwing in a large injector without tuning would likely make the mixture richer than can be compensated for, kill econom, dilute oil and probably damage the cat or wreck other such havoc...



Currently project 07 HHR gets decent mileage on the road at speed, but low speed operation seems excessively inefficient. I did a mock up with several loose parts and think the injectors may be sitting lower than I thought. The fix may be adding 1/8" spacer between the fuel rail and the engine so the fuel rail and subsequently the injectors can sit higher. This would raise the injectors tip to the same height range as the stock injectors. I might be puddling fuel at idle speed.

Unfortunately Winter says "no work on cars right now". the BF Goodrich tires took real well to this mornings ice storm. I had to work it to break traction while other cars where hanging out in the gutter like a really bad bowling alley...

Rocket Surgeon!

Spacers installed, washers at .1050" thick, I do not think that was quite right. fuel trims kicked up some at idle and at cruise. I think the lower Orings are not seated tight leading to slight unmetered air. Will try larger o-ring.


but.... I found a different stock injector to try: 12582219 a 25lb injector from a 05-10 cobalt or 07-10 G5 ecotec?
https://injector-rehab.com/knowledge-base/flow-rates/
This seems much more promising.

Oldblue

From the 2.2 Cobalt, G5 list

https://www.gmpartsdirect.com/oem-pa...ector-12582219

PulpFriction

You may want to check this out then:

https://www.ebay.com/i/233353090530

RJ_RS_SS_350

I guess I don't understand what all the hullabaloo is about. If the factory injectors lasted 12-13 years, that's not terrible, and may be an anomaly. We haven't had a lot of reports of injector failure here on the site.

Just seems like a lot of trouble for a car that a new set of injectors may outlast your Gf's ownership period.

Rocket Surgeon!

but...
chevyhhr.net/forums/general-hhr-4/happy-trails-folks-end-line-4-me-9158/
chevyhhr.net/forums/problems-service-repairs-42/p1174-17812/
chevyhhr.net/forums/problems-service-repairs-42/intermittant-p1174-fuel-trim-cylinder-balance-29074/
chevyhhr.net/forums/problems-service-repairs-42/p1174-40267/
chevyhhr.net/forums/problems-service-repairs-42/bad-fuel-injector-already-7049/
chevyhhr.net/forums/problems-service-repairs-42/p1174-fuel-trim-cylinder-balance-43947/
chevyhhr.net/forums/problems-service-repairs-42/cel-fuel-injector-18749/
chevyhhr.net/forums/problems-service-repairs-42/p1174-code-misfire-code-46521/

Fair of me to observe that I too could not find any hullabaloo in those threads, but I did find many people with 06-07 cars that came equipped with the suspect injector type, and there was more stuff found when I googled TSB 08-06-04-001B and read forum post after forum post. Among the information discovered here and elsewhere is that some of the events of injector failure happened when these cars were new, some less than a year old, some less than 10,000 miles..... Perhaps they may they last 12-13 years in some cases, but there is plenty of antecedent evidence of relatively short "proper" service life, as well as years and years of troubled operation. Some people can and will run a car as long as it will still go.

Only a very few posts I crossed identified cars that had this code that were not 06-07. It is almost exclusively a 06-07 problem.

I can't knock this, because I agree......... I love cheap but good cars, but I do need this car to do it's job while it lasts. Besides, mileage is only 107,000. She's a baby!

p.s. I thought I was clear that I am doing this for posterity?
I would like others to be aware of the issue and be able to share a simple cost effective field solution.
I have written other tutorials over the years, and intend to do the same here.
Plus GF really likes this car so when necessary I might just buy her a replacement HHR, and a replacement HHR for that one, and a replacement HHR for that one, and a replacement HHR for that one.... and then next year maybe she'll look at something different... lol

Rocket Surgeon!

HOLY COW... THESE CARS DO NOT HAVE INLINE FUEL FILTERS?
chevyhhr.net/forums/general-hhr-4/why-no-line-fuel-filter-14359/


WHAT WITCHCRAFT IS THIS? What engineer failed?
While there is a pre-pump filter, there is nothing to catch detritus the pump generates as it wears.


I quickly researched and determined that all 06-11 HHRs do not have inline filters. An 05 cavalier with ecotec does, but a 2015 buick verano with ecotec does not. this must be a new industry standard...

I need to do Orifice analysis on the injectors I am examining. I need a set of nano sized pin gauges.

firemangeorge

Uh. Lots of cars don't have inline fuel filters. Even my 1998 Dodge 1500 pickup doesn't have one.