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New mods, complete with trouble codes

R

rel3rd

Guest
Quick history: Car is a 1985, and has 4+3 transmission...
I just swapped on a set of new, better (than stock) flowing heads, 1.6 rockers, Hedman Elite longtubes, with new 2-1/2" front Y pipe, Ported Edelbrock base, Ported and Siamesed plenum/SLP runners, and an adjustable fuel pressuire regulator. I also deleted AIR pump and it's supporting hardware.

I had a few vacuum leaks, big ones, that have been corrected.
I also checked and reset TPS to .54v. It was at .65v when checked.

After a short drive, I get a CEL lighting up and when I pulled the codes, I have a 13 and a 42.

From what I could find in this little code book,
Code 13 says:
O2 sensor signal stays LOW ("lean") during warm cruise OR sensor cicuit is open.

I'm wondering if this code is from when I first got it running and had all the vacuum leaks? I did not "clear" them from the other day, or as of yet.

Code 42 says:
Electronic Spark Timing ("EST") circuit - open or shorted to ground during engine run
OR
Direct Ignition System ("DIS") fault - bypass circuit open or shorted to ground during engine run.
OR
Fuel cutoff relaycircuit - open or shorted to ground.

I'm not sure where to head on the Code 42 issue...

FWIW, car seems to have a dead or weak cylinder at low rpm/higher load times...like when first taking off, or if I try to cruise at low rpm in OD...it'll buck like crazy and acts as if it has a dead cylinder...
Car "feels" pretty strong at WOT. Idle is a little rough, and acts like a bad spark plug or cap/rotor problem, so I plan to change them as well...unless the problem is related to the codes.

Any help or ideas are appreciated...:cheers:
 
Joined
Aug 30, 2002
Messages
1,533
Location
Colorado Springs, CO USA
Corvette
84 Z51 auto R.I.P. 89 black roadster SOLD
42: the EST bypass didn't get disconnected did it?

13: with that engine combo you're not trying to run with the stock chip are you?

Bill
 
R

rel3rd

Guest
42: the EST bypass didn't get disconnected did it?

13: with that engine combo you're not trying to run with the stock chip are you?

Bill


Thanks for the reply Bill.
It appears to be OPERATOR ERROR on the Code 42....:bash

It seems that SOMEONE may have somehow left the EST wire unplugged after I checked base ignition timing yesterday....;LOL

Yes, I am still running stock ecm/chip.

I never did reset codes the other day after driving home (from garage where I did the mods, 30 miles away) and getting the "first" CEL. I had some BAD vacuum leaks due to an issue with plenum and runner mating, as well as a poorly sealed pcv hose on the driver's side of the base intake, where it connects to metal tube.
After I fixed vacuum leaks, I literally had to turn hard idle screw down over a full turn to get idle at 750 or so. I also no longer smell the very rich, eye burning fumes since that was done. And idle is much smoother, cleaner and all around better sounding now.

I'm "hoping" that was the cause of the Code 13, but I really need to disconnect battery, plug in EST wire, and drive it today to see if CEL stays out.
 
Joined
Aug 30, 2002
Messages
1,533
Location
Colorado Springs, CO USA
Corvette
84 Z51 auto R.I.P. 89 black roadster SOLD
re code 42: been there done that! :L

re code 13: I'm no TPI expert...but having to do such a major adjustment to the mechanical idle stop would make me suspicious of a still existing vacuum leak. Aside from that...with the increase in air flow through that thing (siamesed runners, heads, long tubes...etc)...that stock chip ain't gonna cut it. You're going to HAVE to do some tuning. You really need to watch that A/F ratio, especially at WOT. With such an increase in air flow you're flirtin' with disaster by running lean at WOT...that's BAD news.

Bill
 
R

rel3rd

Guest
..but having to do such a major adjustment to the mechanical idle stop would make me suspicious of a still existing vacuum leak.

Bill

Bill, I may have not been clear in my last reply. The idle needed to be turned down because when I had the vacuum leaks, I had to turn it way up to keep the car from stalling due to low idle.

I disconnected the battery for a while today, but when I hooked it back up and started the engine, it has a noticeable miss at idle...I'm hoping as soon as that nagging issue has been resolved, the car will be ready to roll...:beer
 

jmrl98

Member
Joined
Oct 19, 2006
Messages
19
Location
Hazel Park MI
Corvette
85 4+3
rel3rd, is your o2 sensor heated? If not, with the headers, therein lies the code 13 - happened to me with my 85 when I put headers on.
 
R

rel3rd

Guest
rel3rd, is your o2 sensor heated? If not, with the headers, therein lies the code 13 - happened to me with my 85 when I put headers on.

Sorry. I thought I updated this already.

Stock O2 sensor is fine where it is. I welded a bung 10" away from driver's side cylinder head in header tube #7. After many headaches I finally brought home a digital infrared thermometer and discovered that cylinder #7 header tube was only getting to 100 degrees + or -, so the Code 13 was indeed due to no and/or low O2 readings like the code says, but it was because the cylinder was not having any combustion. The SLP runners are so close to the #7 and #2 injectors that the #7 injector was not getting a good connection 90% of the time.
Had plenty of compression, plenty of spark, but no fuel...:ugh

Tweaked the injector terminals a little and so far, so good...no codes and runs absolutely great! I'm glad it turned out to be something minor. I could have done without the stress, but all is good now. :upthumbs

Thanks for the replies and tips everyone. :beer
 

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