Really odd problem with '6870 ('85TPI)
11-24-2004, 06:32 PM
#1
TGO Supporter
Thread Starter
Join Date: Jan 2003
Location: Australia
Posts: 519
Likes: 0
Received 0 Likes
on
0 Posts
Really odd problem with '6870 ('85TPI)
I am trying to help a friend fix an 85 tpi car.
The story goes like this: Friend buys POS car that was originally a 350tpi. It was running rich as anything, fouling plugs etc..
I went thru all the normal stuff, checked all the sensors, injectors pulled out and tested, cold start injector not leaking etc and found no explanation. I am a competent home mechanic, built a few engines, lots of chip tuning etc....
Further investigation reveals that the block no. is actually a 305! Its been swapped! So I look at the .bin ($1F) in tunercat and see that it doesn't have a normal BPW or injector constant based on engine and injector size etc, what it appears to have is a table called 'Injector Pulse Width vs Load Value', this appears to be the same thing?? Is this correct??
So i lean this table out by 20% as a test, and put it back in the reset ecm..
Start the car up while watching winaldl and see that it goes closed loop, starting at about 600mA on the oxy sensor, so i watch the BLM/INT's expecting them to attempt to work toward 128ish. The INT started at about 118, not too bad.. But from this point it worked its way down to 68 and the exhaust got richer as indicated by the mV and black smoke!!!
Whats going on here?? The ecm knows its slightly rich initially (600mV) the INT's show slightly rich also (118), but it chooses to ADD fuel, driving the mV to 0.9xx and the INT's to 60's.. Its like its working in reverse?
Whats going on, I'm pulling my hair out with this POS!!!
Thanks for reading.
The story goes like this: Friend buys POS car that was originally a 350tpi. It was running rich as anything, fouling plugs etc..
I went thru all the normal stuff, checked all the sensors, injectors pulled out and tested, cold start injector not leaking etc and found no explanation. I am a competent home mechanic, built a few engines, lots of chip tuning etc....
Further investigation reveals that the block no. is actually a 305! Its been swapped! So I look at the .bin ($1F) in tunercat and see that it doesn't have a normal BPW or injector constant based on engine and injector size etc, what it appears to have is a table called 'Injector Pulse Width vs Load Value', this appears to be the same thing?? Is this correct??
So i lean this table out by 20% as a test, and put it back in the reset ecm..
Start the car up while watching winaldl and see that it goes closed loop, starting at about 600mA on the oxy sensor, so i watch the BLM/INT's expecting them to attempt to work toward 128ish. The INT started at about 118, not too bad.. But from this point it worked its way down to 68 and the exhaust got richer as indicated by the mV and black smoke!!!
Whats going on here?? The ecm knows its slightly rich initially (600mV) the INT's show slightly rich also (118), but it chooses to ADD fuel, driving the mV to 0.9xx and the INT's to 60's.. Its like its working in reverse?
Whats going on, I'm pulling my hair out with this POS!!!
Thanks for reading.
11-25-2004, 07:35 AM
#2
Moderator
iTrader: (1)
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,408
Likes: 0
Received 217 Likes
on
203 Posts
Car: check
Engine: check
Transmission: check
The INT dropping is removing fuel. So the ECM knows it is too rich and is pulling fuel out. I'd look into what size injectors are in the engine.
RBob.
RBob.
11-25-2004, 07:52 AM
#3
TGO Supporter
Thread Starter
Join Date: Jan 2003
Location: Australia
Posts: 519
Likes: 0
Received 0 Likes
on
0 Posts
ohhh, of course it is, I was getting a bit muddled there!!
The injectors have been checked out as ok, but I didn't speak to the guy who did the job. The info i received says that he was of the opinion that they were 'about the right size'.....
Just to prove a point, i burnt chips with the 'Injector Pulse Width vs Load Value' table at 80, 70, 50 and even 20% of its original usec values and it still ran way rich at closed loop idle..
It goes closed loop about when expected, but the O2 stays at 8-900mV, and pumps black smoke...
Whats the lowest pressure these injectors can run before poor atomization becomes an issue?? I'd like to back it off as a means of testing..
The injectors have been checked out as ok, but I didn't speak to the guy who did the job. The info i received says that he was of the opinion that they were 'about the right size'.....
Just to prove a point, i burnt chips with the 'Injector Pulse Width vs Load Value' table at 80, 70, 50 and even 20% of its original usec values and it still ran way rich at closed loop idle..
It goes closed loop about when expected, but the O2 stays at 8-900mV, and pumps black smoke...
Whats the lowest pressure these injectors can run before poor atomization becomes an issue?? I'd like to back it off as a means of testing..
Thread
Thread Starter
Forum
Replies
Last Post