Car:
1984 244 GL non-turbo B23F 4 cyl automatic
***This is a perhaps a real nit-picky account of fine tuning, but I'm convinced there's some small issue somewhere that i'd like to solve and get my car idling 100% stock.
STORY:
California car purchased about 14 months ago, sat for some years but was in amazing cosmetic condition with ~160000 miles. over the last year I have put some major elbow grease into the vehicle and completely overhauled almost everything outside the engine block. It's driven approx. 15,000 miles in the last year and only broken down once (alternator died). Stunningly, I've routinely measured it at 27 mpg on the freeway (without roof rack). however, city driving I have measured at anywhere from 12-18 mpg since I live in a crowded metro area. City mileage still seems very low... the car had issues with rich fuel mix when I first started working on it but replacing the ECU and a handful of other repairs brought it up to snuff enough to pass CA smog with flying colors last summer.
the car runs great, looks great, would drive across the USA tomorrow, but...
ISSUE:
I've been attempting to fine tune the idle on my car and I'm noticing some strange inconsistencies.
I've been having an issue where I drive to work (short distance) in the morning, and in the afternoon (approx 8/9 hrs later) the car often stumbles on the first start.
I recently did a routine throttle body clean, replaced the gasket, cleaned flame trap etc. It looked pretty clean already- interior of intake manifold was sparkly clean, intake bendy hose inspected for holes, air filter clean, MAF cleaned ~2 months ago and output voltage tuned to 1 volt.
While I was cleaning the throttle body I noticed a trickle of gas on the vacuum end of my fuel pressure regulator- ok, bought a new OEM fuel pressure regulator and installed successfully.
When I returned to tuning the idle, I found that closing the adjustment screw all the way only brought the engine down to around 1200 RPM. I wiggled the electrical connector on my position sensor and it dropped back down to a rough 750 and needed to have the air manually adjusted up to ~1100rpm to smooth it out. I cleaned the contacts on it and reinstalled the plug.
The main issue is that when the car is warm, the idle should be stable at around 750-900rpm as far as I know. the lowest idle I can tune in that is consistently smooth is around 1100 RPM fully warmed.
Almost all the fuel and air regulating parts/gaskets/hoses have been replaced in the last year as I've restored the vehicle. All vacuum hoses tested for leaks, none. It even has new engine wiring looms (original was a crumbly mess that disintegrated in my hands as I tore it out). I have not performed any mods linking this to that to increase fuel for cold weather etc. as indicated several places online, it's as stock as they come.
As far as I understand it, the thing should be holding a constant idle no matter how i've been driving it except for when it is first warming up. I am aware that the b23f supposedly runs a bit lean when cold and can idle a little rough until warming up- confirmed.
*The problem is every time I drive the car the idle seems to change. sometimes it's very stable at 900, sometimes it's up around 1300-1400 if I've just come off a long drive on the freeway. Even when the car is holding a 'smooth' idle, it has a small periodic shudder that I can feel from the drivers seat. the last thing is that if I leave it idling, about once every 15/20 minutes or so the engine will surge to above 2000rpm for ~1 second and then return to normal.
Have I gone too far? is this just normal gremlins for an old B23F?
I have a multimeter and some basic electrical knowledge so I'm comfortable taking readings if people need. the car is almost 100% dialed, but I can't seem to get this last little mystery solved.
throttle position sensor? electrical? bad ground? weird relay? ECU idle circuit about to 'splode?
Anything that would help point me in the right direction would be helpful.
I'm feel like I might be expecting too much out of an old engine, but maybe not?
BONUS: Information about replacing electrolytic caps in the 503 ECU (I think there are a couple, it's been a while since i've opened it). can I just swap them out without having to do some crazy cryptic calibration procedure?
1984 244 GL non-turbo B23F 4 cyl automatic
***This is a perhaps a real nit-picky account of fine tuning, but I'm convinced there's some small issue somewhere that i'd like to solve and get my car idling 100% stock.
STORY:
California car purchased about 14 months ago, sat for some years but was in amazing cosmetic condition with ~160000 miles. over the last year I have put some major elbow grease into the vehicle and completely overhauled almost everything outside the engine block. It's driven approx. 15,000 miles in the last year and only broken down once (alternator died). Stunningly, I've routinely measured it at 27 mpg on the freeway (without roof rack). however, city driving I have measured at anywhere from 12-18 mpg since I live in a crowded metro area. City mileage still seems very low... the car had issues with rich fuel mix when I first started working on it but replacing the ECU and a handful of other repairs brought it up to snuff enough to pass CA smog with flying colors last summer.
the car runs great, looks great, would drive across the USA tomorrow, but...
ISSUE:
I've been attempting to fine tune the idle on my car and I'm noticing some strange inconsistencies.
I've been having an issue where I drive to work (short distance) in the morning, and in the afternoon (approx 8/9 hrs later) the car often stumbles on the first start.
I recently did a routine throttle body clean, replaced the gasket, cleaned flame trap etc. It looked pretty clean already- interior of intake manifold was sparkly clean, intake bendy hose inspected for holes, air filter clean, MAF cleaned ~2 months ago and output voltage tuned to 1 volt.
While I was cleaning the throttle body I noticed a trickle of gas on the vacuum end of my fuel pressure regulator- ok, bought a new OEM fuel pressure regulator and installed successfully.
When I returned to tuning the idle, I found that closing the adjustment screw all the way only brought the engine down to around 1200 RPM. I wiggled the electrical connector on my position sensor and it dropped back down to a rough 750 and needed to have the air manually adjusted up to ~1100rpm to smooth it out. I cleaned the contacts on it and reinstalled the plug.
The main issue is that when the car is warm, the idle should be stable at around 750-900rpm as far as I know. the lowest idle I can tune in that is consistently smooth is around 1100 RPM fully warmed.
Almost all the fuel and air regulating parts/gaskets/hoses have been replaced in the last year as I've restored the vehicle. All vacuum hoses tested for leaks, none. It even has new engine wiring looms (original was a crumbly mess that disintegrated in my hands as I tore it out). I have not performed any mods linking this to that to increase fuel for cold weather etc. as indicated several places online, it's as stock as they come.
As far as I understand it, the thing should be holding a constant idle no matter how i've been driving it except for when it is first warming up. I am aware that the b23f supposedly runs a bit lean when cold and can idle a little rough until warming up- confirmed.
*The problem is every time I drive the car the idle seems to change. sometimes it's very stable at 900, sometimes it's up around 1300-1400 if I've just come off a long drive on the freeway. Even when the car is holding a 'smooth' idle, it has a small periodic shudder that I can feel from the drivers seat. the last thing is that if I leave it idling, about once every 15/20 minutes or so the engine will surge to above 2000rpm for ~1 second and then return to normal.
Have I gone too far? is this just normal gremlins for an old B23F?
I have a multimeter and some basic electrical knowledge so I'm comfortable taking readings if people need. the car is almost 100% dialed, but I can't seem to get this last little mystery solved.
throttle position sensor? electrical? bad ground? weird relay? ECU idle circuit about to 'splode?
Anything that would help point me in the right direction would be helpful.
I'm feel like I might be expecting too much out of an old engine, but maybe not?
BONUS: Information about replacing electrolytic caps in the 503 ECU (I think there are a couple, it's been a while since i've opened it). can I just swap them out without having to do some crazy cryptic calibration procedure?
