21lb injectors excessive on otherwise stock M20?

[blitzkrieg59]

I picked up an '89 325i at the end of October and the PO told me the M20 was stock outside of 21lb injectors, a Dinan chip, and a cone filter.

I haven't found any information that supports a notion of the Dinan chip requiring/working better with 21lb injectors.

Seems to me that these injectors might be a bit too hefty for an otherwise stock M20. The car does seem to run rich. But I'm not sure that's the result of the injectors or a whacked out sensor somewhere. Would there be any advantage to swapping the 21lb injectors out for 19lb injectors or should I just leave well enough alone?

[ButtJuice]

M50 injectors, (17.5 lbs?) would be the highest I'd go for what you have.

[blitzkrieg59]

Thanks for the suggestion.

[digger]

you need to find out what the chip was "designed" to use. then install those and reset adaptions (leave the battery unlugged for about 30min).

or get a good chip for SQUID and install relevant injectors to suit as the Dinan stuff will be Meh

[squidmaster]

Doing injectors that big without a tune for that flow rate would cause some issues. No reason to go that large on a stock setup anyhow.

[blitzkrieg59]

I'm leaning toward replacing the Dinan chip with one of your units, Squid. Would it be foolish to hit you up for a chip tuned for 91 octane and 21lb injectors considering I don't see a cam, MAF conversion, or stroker build in the car's near future? I'd like to solve my rich running condition/poor mileage issue and it'd be nice if I could do it without spending the extra dough for rebuilt M50 injectors — budgets suck. But I don't want to half-ass my daily driver either.

[nando]

if the injectors are in good shape, it won't hurt to have a chip made for them. the Dinan tune isn't worth much anyway. I'd go for the SSSquid chip.

The only real downside is the injector PW will be smaller at lower loads. it's probably not that big of a difference in this case but sometimes you can run into control issues where the commanded injector time is equal to or less than the injector response time. That would really only apply on an injector that is much larger than required (or one with a relatively poor response time).

[squidmaster]

I'm leaning toward replacing the Dinan chip with one of your units, Squid. Would it be foolish to hit you up for a chip tuned for 91 octane and 21lb injectors considering I don't see a cam, MAF conversion, or stroker build in the car's near future? I'd like to solve my rich running condition/poor mileage issue and it'd be nice if I could do it without spending the extra dough for rebuilt M50 injectors — budgets suck. But I don't want to half-ass my daily driver either.

People with 100% stock cars get chips from me all the time, so don't worry you're good to go. There are always gains to be made.

if the injectors are in good shape, it won't hurt to have a chip made for them. the Dinan tune isn't worth much anyway. I'd go for the SSSquid chip.

The only real downside is the injector PW will be smaller at lower loads. it's probably not that big of a difference in this case but sometimes you can run into control issues where the commanded injector time is equal to or less than the injector response time. That would really only apply on an injector that is much larger than required (or one with a relatively poor response time).

Which is why you gotta tune the injector dead time as well for larger injectors ;)

[digger]

People with 100% stock cars get chips from me all the time, so don't worry you're good to go. There are always gains to be made.



Which is why you gotta tune the injector dead time as well for larger injectors ;)

and how do you know what that is without the specific injector to measure? all 21lb arent created equally

[jeffnhiscars]

and how do you know what that is without the specific injector to measure? all 21lb arent created equally

I would think you map to spec to sell chips off the shelf. Beyond that you find a dyno and dial it in.

[squidmaster]

and how do you know what that is without the specific injector to measure? all 21lb arent created equally

all 14.5 aren't created equally either, but the factory mapping has dead times for those-- there wasn't a tuner sitting in each e30 as it came off the assembly line to change settings for each car. You can't create a perfect map for every since injector ever made, but you can mitigate the dead time issue to a degree. Since the 21lb injectors that people use are pretty much all the pink tops, I developed a pretty good base map for those injectors.

And you're talking about a 1-2% difference between each produced injector, if that. So, in the end, it's not much of a difference.

I would think you map to spec to sell chips off the shelf. Beyond that you find a dyno and dial it in.

exactly! :)
though for injector dead times you don't really need a dyno. You start out tuning the dead times at idle

[Advrider639]

This might be a stupid question, but I am new to this. Specifically for you Squid, just looking at a 325i chip from you set up with stage 1 and 19lb injectors does it matter if my car is an automatic and I might potentially covert it to manual down the road? Would I have to get a entirely new map?

Only reason I ask is that I didn't see anything on your web page that asked either or, but the chips that Turner sells it does ask you to specify what gear box you have.

Thanks.

[digger]

all 14.5 aren't created equally either, but the factory mapping has dead times for those-- there wasn't a tuner sitting in each e30 as it came off the assembly line to change settings for each car. You can't create a perfect map for every since injector ever made, but you can mitigate the dead time issue to a degree. Since the 21lb injectors that people use are pretty much all the pink tops, I developed a pretty good base map for those injectors.

And you're talking about a 1-2% difference between each produced injector, if that. So, in the end, it's not much of a difference.



exactly! :)
though for injector dead times you don't really need a dyno. You start out tuning the dead times at idle

I take your point about it being small error but i wasn't meaning variations between the same p/n injectors rom manufacturing variations. when you get a 24lb injector for example there are often several different p/n some plastic body some metal body etc etc I've always wondered in the characteristics are different enough to matter

[squidmaster]

I take your point about it being small error but i wasn't meaning variations between the same p/n injectors rom manufacturing variations. when you get a 24lb injector for example there are often several different p/n some plastic body some metal body etc etc I've always wondered in the characteristics are different enough to matter

It mostly depends on metal body vs plastic body. The newer styles tend to be a bit quicker than the clunky ol' metal ones. I find it's always beneficial to ask my customers which injectors they're using, and many customers just shoot me over the part number (ebay sells "24lb" injectors that, according to their spec sheet, actually flow 22.5lb.... so....)

[squidmaster]

This might be a stupid question, but I am new to this. Specifically for you Squid, just looking at a 325i chip from you set up with stage 1 and 19lb injectors does it matter if my car is an automatic and I might potentially covert it to manual down the road? Would I have to get a entirely new map?

Only reason I ask is that I didn't see anything on your web page that asked either or, but the chips that Turner sells it does ask you to specify what gear box you have.

Thanks.

I try to make the tunes as universal as possible, so they have automatic programming in them as well, so you can use it in either a manual or auto.