mauijerky

I've had my 91 L03 for about 4 months now. Got her cheap but not running. Put in new fuel pump, all sensors, new distrib., wires, plugs. Got her running great and is my daily driver. Its mostly stock but with TES headers and all smog systems removed. Although, a couple weeks ago got code 43. She was losing power when accel, would bog at tip-in, or die out at idle. Restart an be fine. I replaced the knock sensor and ESC module. That fixed the code 43, and its back to making good power when accel. I thought prob was solved, but I still experience the occasional tip-in bog and stalling at idle. Its not consistent, though. Also, on first (cold) start-up, IAC is stepped out during warm up as usual. A few seconds after putting it in gear, the idle will go up quite a bit higher until usual warm up phase brings it back down. Datalog shows the IAC steps increasing at this moment. I don't think the idle jumping up in gear is supposed to happen. I haven't cracked open the ECM yet to see if there is a different chip than stock installed. Previous owner told me he put in bigger injectors. I asked if they were 350 injectors, but he only knew they were "bigger". I imagine the next up from the 55 lb/hr would have to atleast be 61. I'm sure there was no tuning done to accommodate the bigger injectors.

My bog/stalling issue is only recent, but could bigger injectors without tuning cause this? Also, what would cause the IAC to considerably increase idle a few sec after putting in gear? Idle is normal when warm. Purrs at about 600rpm at red lights. Just stalls once in a awhile then runs fine after restart. EGR is blocked off, and removed PCV (re-purposed the AIR check valve at header as crankcase vent). Only thing using manifold vacuum is the EVAP canister, HVAC controls, and the brake booster.

Schurkey

Fix that first.

mauijerky

Blocked off EGR and venting the crankcase through the exhaust is not something that needs to be "fixed". I put on an EGR plate to take it out of the equation. It only throws the trouble code when cruising at highway speed. Which I don't do very often on an island. There is no smog check here either. I pulled off the PCV vacuum line and capped off the port on the intake. The vapors now vent out the exhaust instead of the being sucked back into the combustion chamber. My problems starting occurring before making these changes, anyways.

Everything started happening when I got the code 43. I found old thread stating the ECM will intentionally advance the timing until it detects knock as a method of testing the knock system. I was thinking this was happening on my car since the idle would jump up a little bit then at times almost stall shortly after going in gear. After replacing the knock sensor and the EST module, the code 43 never came back and my car runs way better now, but still idles during warm up then either almost stalls or does stall. After warm up, it will run great but sometimes stumble off the line. I guess I need to capture this on a datalog. Of course logging has been hit or miss. I sometimes have issues with the stream stopping shortly after connection, or the car runs fine when the stream stays connected during my drive. I'm going to rebuild the TBI next. I'm almost down to the ECM being the prob. I wanted to get a different ECM anyways. That way I can mod it with rbob's EBL at leave the original ECM untouched.

Schurkey

Have you considered that EGR is an excellent part-throttle anti-detonation device, and without it the engine may be working the knock sensor/retarding timing far more than it should? You'd need extensive fuel- and spark-tuning to compensate for lack of EGR in terms of part-throttle detonation.

Have you considered that carburetors and fuel injection (IAC) are calibrated to accommodate the air flow from a PCV valve at idle? That dumping crankcase vapors directly into the exhaust could not only poison the catalytic converter, but also provide false air to the O2 sensor? (depending on the position of the sensor) That race cars that use venturi-effect to vacuum the crankcase have nozzles welded into the exhaust to create considerable suction, and your system doesn't? That failure to PROPERLY evacuate the crankcase fumes reduces oil and bearing life?

Why in hell would you defeat the PCV system? It's the most-reliable, simplest, most-effective pollution control device ever invented, with the side-effect of making the engine last longer!

Fix this first, even if it doesn't take care of the problems you're complaining about, it STILL NEEDS TO BE DONE.

Schurkey

What timing. I just got a notice from SEMA via e-mail. Hawaii legislators are fed-up with boneheads that abuse emissions controls and install excessively-loud exhaust systems. SEMA is opposed to this legislation, which has numerous flaws.

mauijerky

Wow!! I sure got someone fired up here. Technically you are not supposed to modify or remove and factory exhaust or emissions systems here. That is illegal. Although, it is not normally checked for during the annual safety inspections. Also, its mainly the modded asian cars and lifted pickups that get profiled here. Every once in a while local law enforcement will "cull" the crowd and dish out tickets for these violations.

Yes, ALL of the emission systems have been removed from my car. Cat was already removed when I got the car, AIR pump was knocking so I pulled it off. I only recently did the EGR/PCV thing. As I said, I was having the same exact issues before so. So i don't see how its related. The EGR only activates under certain conditions anyhow. I blocked it off to determine if it was stuck open, but I don't think it was. The PCV is just one of those for the "fun of it" things. Its only been that way for a few days. Oh, and the race car crankcase "header" vents is just a one way check valve that only allows the air to enter the exhaust. And YES the venturi effect... The AIR check valve is the same exact thing, and a vacuum IS formed there when the motor is running. (I made sure of that) This is why it can be used as a vent. (If you are concerned about my motor not being properly vented.) There's no gains or losses to it. I just did because the check valves where already there on my headers. I would never recommend to anyone else to modify the PCV system. I might put it back to stock when I rebuild the throttle body.

mauijerky

Ok, YES the EGR effects timing and fueling when activated. I don't think the EGR has been working since I got the car. It was getting code 32 off the bat. I will get a new one and see what happens. Although, I still don't think it should effect off idle. Just part throttle, right?