- Thread starter
- #21
boomdriver
Well-known member
C4C5specialist,
Thanks for getting involved.
I am not sure which brand o2 sensor is currently in there. It's fairly well welded itself in place, so I have to get it on a lift and heat it to remove. Its been there for 10 yrs or more since the stock Y-pipe was removed...
I have a NEW Bosch to be installed, or is the delco a better choice?
Was also going to get the cat tested either by gas and/or temps at ends.
Cannot get printed info yet because nobody so far has the equip to plug in and see what the ECM sees. Around here the shops all moved on and went to later model scanning. I guess classics are'nt that interesting to these techs in this area. One shop tells me that nobody has an OBD1 car anymore....
I guess it is older than some of the techs...wow.
Schrade, I WILL go get a jug of everclear before the weekend. That "store" was closed on sunday so I had to settle for methanol rather than ethanol. I never knew the exact difference between the 2 except that one was for drinkin and the other was for blindness.
Geek,
I wish you guys would'nt worry so much about my reasons for modifying the engine. They were the same as anyone that wants to go faster and have fun with their car. It was torn apart for rebuild and the decision was made to upgrade while apart. NOT to BOLT-ON stuff and hope for the best. The plan was to build and it was very successful.
But, to clarify a couple things,
It WAS NEW, upgrades done on the table, balancing done at the machine shop, and electronic control calculated and set up to match the physical changes. I have only built 2 L-98s but many multi-cyl motorcycle race engines both 2 & 4 stroke for straight line and road course competition. I had to stop short of my goal of all forged parts in the bottom end because of budget limitations.
Notice the little things like the compression ratio...Done intentionally so I would not have to mix gas (av gas +pump gas) or retard the timing or flatten out the advance curve to prevent knocking. It can run 89oct but it has to be retarded a cpl degrees to do that in the summer.
Balanced bottom end, so that upper end RPM could be safely enjoyed when running out 1st, 2nd gear and drop it into the middle of the powerband shifting into 3rd for stop-lite steeple-chase.
Another goal was to keep the stock engine equipment (for smog and resale) but get a REAL gain in HP and not just take some from the other end of the power band, (like renegade owners will likely suffer).
This engine with the big exhaust and 4 corsa exit pipes would rev from idle to 6000 instantly, and almost do it as fast when it was in gear. It's been a VERY good build. The exhaust was later replaced with a muffled system so I could hear the phone or talk to someone in the car.
I've detuned (mufflers, main-cat, intake filter, etc) to make it more civil and quieter, and focused lately on restoration of the appearence and the interior finish. I am trying to get it back to "new condition". But I do not have a garage to work in, or a scanner that reads and prints out a report, I can only go as far as what a digital multi meter and whatever lites, buzzers and personal experience will tell me. I am here asking the professionals for their opinion becasue my C-4 experience is limited to 5 cars,. only 2 of which I built, and I see people in here that lay hands on them everyday and have done so for many years. A fresh pair of eyes is always helpful.
Moving forward,
It does not have oil passing the rings on #7, with compression test as proof.
If rings were an issue, 7 would have been low. That was the point of the compression testing. This was to rule out physical damage and oil as the reason for the dirty plug. Had the comp been low in #7 and I was able to get it up temporarily by squirting oil into the cyl, thats a sure bet that there is ring damage or wear. But, thats not the case here. The cyl is tight.
I greatly appreciate your help, as I am aware that there are many people here that are smarter than I ever will be.I need your expert advise in order to learn,and that is really the goal. By presenting all the available info for you guys to digest and consider, I can make decisions on what & how to approach the problem tomorrow. Anybody can throw the problem in the lap of some shop and say "fix it". I would rather understand what was wrong, how and why it is like that. That comes from careful study of the condition and learning from those that have a better education and seen things that I have not.
I'll work today to get a printed report and post it here. I have no idea where I'll get it, but someone HAS to have the scanner to do more than read DTCs and actually interface with the ECM thru the ALCL. I cannot believe a city this big and they all abandoned OBD1 diagnostic equip.
Current facts include:
no oil burning.
no oil/exhaust blow-by thru pcv.
engine tuned to factory spec with factory ecm & prom.
inj solenoids all test ok, fuel press leakdown was good.
operating temps are currently factory spec.
One spark plug thats dark brown. & others that are white. All are new.
Questions at this point:
is A.I.R. system operating correctly? needs to be tested.
is #7 injector shooting excessive fuel when its pulsed?
Is the cat dead?
is the o2 sensor partially to blame?
Because of discussion I now have eliminated many possible issues and repaired several things that were unknown until digging into the emissions system. Anyone of these things could have been more trouble somewhere down the road, but thats been prevented with the help of this group.
I'll continue to attack the issues with the advise of the group, as I feel that its been sound, rational advise and not BS which only serves to distract.
It's time to make some calls and find a real diagnostic scanner in this hillbilly town.
Again,
Thanks guys.
Thanks for getting involved.
I am not sure which brand o2 sensor is currently in there. It's fairly well welded itself in place, so I have to get it on a lift and heat it to remove. Its been there for 10 yrs or more since the stock Y-pipe was removed...
I have a NEW Bosch to be installed, or is the delco a better choice?
Was also going to get the cat tested either by gas and/or temps at ends.
Cannot get printed info yet because nobody so far has the equip to plug in and see what the ECM sees. Around here the shops all moved on and went to later model scanning. I guess classics are'nt that interesting to these techs in this area. One shop tells me that nobody has an OBD1 car anymore....
I guess it is older than some of the techs...wow.
Schrade, I WILL go get a jug of everclear before the weekend. That "store" was closed on sunday so I had to settle for methanol rather than ethanol. I never knew the exact difference between the 2 except that one was for drinkin and the other was for blindness.
Geek,
I wish you guys would'nt worry so much about my reasons for modifying the engine. They were the same as anyone that wants to go faster and have fun with their car. It was torn apart for rebuild and the decision was made to upgrade while apart. NOT to BOLT-ON stuff and hope for the best. The plan was to build and it was very successful.
But, to clarify a couple things,
It WAS NEW, upgrades done on the table, balancing done at the machine shop, and electronic control calculated and set up to match the physical changes. I have only built 2 L-98s but many multi-cyl motorcycle race engines both 2 & 4 stroke for straight line and road course competition. I had to stop short of my goal of all forged parts in the bottom end because of budget limitations.
Notice the little things like the compression ratio...Done intentionally so I would not have to mix gas (av gas +pump gas) or retard the timing or flatten out the advance curve to prevent knocking. It can run 89oct but it has to be retarded a cpl degrees to do that in the summer.
Balanced bottom end, so that upper end RPM could be safely enjoyed when running out 1st, 2nd gear and drop it into the middle of the powerband shifting into 3rd for stop-lite steeple-chase.
Another goal was to keep the stock engine equipment (for smog and resale) but get a REAL gain in HP and not just take some from the other end of the power band, (like renegade owners will likely suffer).
This engine with the big exhaust and 4 corsa exit pipes would rev from idle to 6000 instantly, and almost do it as fast when it was in gear. It's been a VERY good build. The exhaust was later replaced with a muffled system so I could hear the phone or talk to someone in the car.
I've detuned (mufflers, main-cat, intake filter, etc) to make it more civil and quieter, and focused lately on restoration of the appearence and the interior finish. I am trying to get it back to "new condition". But I do not have a garage to work in, or a scanner that reads and prints out a report, I can only go as far as what a digital multi meter and whatever lites, buzzers and personal experience will tell me. I am here asking the professionals for their opinion becasue my C-4 experience is limited to 5 cars,. only 2 of which I built, and I see people in here that lay hands on them everyday and have done so for many years. A fresh pair of eyes is always helpful.
Moving forward,
It does not have oil passing the rings on #7, with compression test as proof.
If rings were an issue, 7 would have been low. That was the point of the compression testing. This was to rule out physical damage and oil as the reason for the dirty plug. Had the comp been low in #7 and I was able to get it up temporarily by squirting oil into the cyl, thats a sure bet that there is ring damage or wear. But, thats not the case here. The cyl is tight.I greatly appreciate your help, as I am aware that there are many people here that are smarter than I ever will be.I need your expert advise in order to learn,and that is really the goal. By presenting all the available info for you guys to digest and consider, I can make decisions on what & how to approach the problem tomorrow. Anybody can throw the problem in the lap of some shop and say "fix it". I would rather understand what was wrong, how and why it is like that. That comes from careful study of the condition and learning from those that have a better education and seen things that I have not.
I'll work today to get a printed report and post it here. I have no idea where I'll get it, but someone HAS to have the scanner to do more than read DTCs and actually interface with the ECM thru the ALCL. I cannot believe a city this big and they all abandoned OBD1 diagnostic equip.
Current facts include:
no oil burning.
no oil/exhaust blow-by thru pcv.
engine tuned to factory spec with factory ecm & prom.
inj solenoids all test ok, fuel press leakdown was good.
operating temps are currently factory spec.
One spark plug thats dark brown. & others that are white. All are new.
Questions at this point:
is A.I.R. system operating correctly? needs to be tested.
is #7 injector shooting excessive fuel when its pulsed?
Is the cat dead?
is the o2 sensor partially to blame?
Because of discussion I now have eliminated many possible issues and repaired several things that were unknown until digging into the emissions system. Anyone of these things could have been more trouble somewhere down the road, but thats been prevented with the help of this group.
I'll continue to attack the issues with the advise of the group, as I feel that its been sound, rational advise and not BS which only serves to distract.
It's time to make some calls and find a real diagnostic scanner in this hillbilly town.
Again,
Thanks guys.
) I just didn't realize yours was modified...and that makes a big difference vs. stock when it comes to this kind of troubleshooting! Just spoke too soon, that's all.
