samsonb

Have a stock 89 with Bosch III 22# injectors. The previous owner put 24# injectors in and I noticed it running rich and also got knock counts when driving. I put in the Bosch III 22# injectors and it runs real lean and knocks alot. Audible knock.

Had a tuner a while back that was looking at it but he quit answering e-mails when I'd send him a new datalogs shortly after getting started. And this tuner bailed in the middle of the tune claiming family problems.

Any suggestions on fixing the lean condition and eliminating the knock?It's audible knock, which isn't good. I was thinking of putting in a mild timing curve like that in an L98 Camaro. Though someone sent me their custom timing curve that would fall in between the Camaro L98 and Corvette L98 timing curve.

Could figure out why it knocks as I put in new EGR valve and checked all the other parts.

tombrammer

If the previous owner lowered the injector constant for the new 24# injectors (if they are not stock and the 22# is stock) and you went back with the 22# injectors w/o setting the inj. constant back to stock then your motor will run really lean.

samsonb

The PO didn't mess with the computer. He just put in the wrong injectors 24# as Accel listed them as fitting.

I noticed it running rich when I started scanning, and also getting knock counts. So put in Bosch III 22#, then noticed it running super lean. i.e. would peg at 160 at times. And also still knocking.

Pretty much just need to fix the BLM's and stop the knock. But I'm thinking the knock would be easy as I'd guess you could just put in a more mild timing curve. Like the curve from an L98 Camaro.

Someone did send me a modified timing curve that looked to be in between the Camaro L98 and Corvette L98 timing curve.

Cliff Harris

When you do a typical "drive around the block" scan, what BLMs do you get and what cells are they in?

What BLM do you get in cell 0?

A 160 (which cell? 15?) indicates that you probably have very high combustion chamber temperatures, which will cause knocking. Timing may not be your problem.

samsonb

I'll do a datalog in Datamaster.

What .bin should I run that datalog on, the stock bin?

And what size injectors should I have it set to, stock?

And should I lower the AFR to 14.1, and set the ALDL adder to 0?

Kevova

I saw some previous threads related to your car; is this the same car? If so, did you ever get it straightened out, or it still on going?

samsonb

Same car same problem. Had a tuner on it a long while back and thought it would get fixed. But he shortly quite responding to e-mails claiming he had family health problems even though he was paid upfront. Was left with a high performance chip that had a few custom tweeks to it. Wanted to just keep it stock but fix the high BLM's and knocks. But running on that latest tune from the tuner, it still runs lean in places and still knocks. The bad thing is it's an audible knock. I had thought of just throwing in a mild timing curve like what is on a Camaro L98 to see what that did to the knocks. But not sure if it is safe to do that?

As I know a lot of Camaro L98 guys will put the Corvette ARAP in, and then reduce the timing curve as the Corvette L98's curve is too aggressive. As the Camaro has iron head and Corvette has aluminum heads.

I did put in a new EGR valve to fix the bad one, and checked the exhaust back pressure, and that tested good. So ran out of ideas on the knock.

Kevova

If vacuum is applied to egr valve at idle will engine stall or try to stall? if not egr passages are restricted, could be cause. What is timing set at?,if advanced reset to stock. Try to get car back to stock base line then if car will run as designed; then you can try mods. Lots of hustlers out there selling dreams. Car should not require 93 octane You could try it. If corrects it is possible to have carbon build up that raises compression to require it. "Sea-foam" I really don't know much about it, but seems to be popular as a decarboner on many sites. I'm sure someone will chime in on the best way to use it in this application. Carbon is responsible for spark knock often. Does engine use or leak oil, blue smoke on start up? As far as fuel system what is short and long fuel trim and what is range the O2 varies should be at least .6 v......ie .2xx to .8xx. I figure we will start over to get car right

samsonb

Old EGR was bad as you couldn't open it up with vacuum. New negative EGR is good and does stall engine if pulling a vacuum on it. Though didn't change anything with the knock. Timing is set at 6* Advance which is stock. Also had a new harmonic balancer to look at to make sure the timing mark had not slipped on the balancer that is on the engine.

Did try Seafoam and the GM Top End Cleaner, and switched to 93 octane. It's possible it could have carbon build up due to it running rich for a few years from the PO putting 24# injectors in it. But already tried Seafoam and GM Top End Cleaner a few times.

Don't really notice any "blue smoke".

On the short and long fuel trim and O2 range, do you get those numbers from the datalog?

samsonb

Attached is a Datamaster datalog with Bosch III 22# injectors and stock car. It's in a Zip file. There's a dead spot in the middle when I stopped to get gas.

The .bin file is an ARAP file with the following changes I made for the datalog:

Spark Advance Added in ALDL Mode Changed from 8.1 to 0.
Injector flow rate Single fire and Double fire changed from 22.4 to 21.
Stochiometeric Air Fuel Ratio changed from 14.7 to 14.1.

Was reading on this site www.scotthansen.net and noticed him mention to avoid the Bosch III 22# as he had to change injectors to 19.8 to get it to run close.

Rohn

High BLM could be exhaust leak... I had same when i installed headers and true duals. Leaked at collector flange to ext pipe.

samsonb

I've looked before and not notice or couldn't see an exhaust leak. I also did a back pressure test to make sure the cat wasn't clogged or something.

I have read some say the rebuilt Bosch III 22# are actually more like a 20# injector.

May some time later on put the Accel 24# injectors back in and set the injectors to 24# and see what that does.

Kevova

I was unable to open Zip file. What known mods? What happens with OEM chip? What is timing at 3K should be under 38 total. Remove AIR hoses if present from exhaust manifolds what does that do to fuel trim?

samsonb

The file should just unzip when extracted.

There aren't any mods. Only thing I'd say would be considered non-stock replacement part would be Bosch III 22# injectors. May look at putting the Accel 24# injectors back in that the PO had in there and setting the injectors in the tune for 24# and see what that does to the BLM's. Those injectors probably have 4-5 years of use, and not many miles. So would think they'd all be good.

It has the same problems with the OEM chip which was why I was having it tuned a while back by a tuner, but ended up getting burned along with others by the tuner and was left with a barely tuned performance chip thing.

Those AIR hoses are a pain to disconnect. But replaced both AIR hose check valves a while back.

I think the lean condition is from the Bosch III 22# injectors. Knock is probably carbon build up as I've checked everything else. There's a lot of different info here on these injectors. But have read some say at the stock pressure the Bosch III 22# aren't really 22# but smaller. Looks like some like the injector and some hate it. And some say the Bosch III spray too differently than the Multec injectors.

I think the Accel injectors I've got are the old type spray pattern.

Accel 150824

www.jegs.com/i/Accel/110/150824/10002/-1

Except mine are yellow.

Rohn

and plug them

samsonb

Put in Bosch III 24# injectors. BLM's are from 124 to 136. It's only at 124 in a couple of cells for a few seconds. Mainly stays at 134 at city cruising. I'd say that would be in the safe range as it would be around +-5 over and under 128. On the next datalog will adjust the AFR from 14.7:1 to 14.1:1. As that is the AFR that seems to be recommended for E10 gas.

Only thing left is to figure out how to tune the main spark table with regards to knock counts and knock retard. Mainly get knock counts when going up a hill, or speeding up on the on ramp getting on the interstate.