Terrible Cold Start Idle ...what Fixes This?
06-16-2005, 12:09 PM
#1
Senior Member
Thread Starter
Join Date: Nov 2003
Posts: 227
I used to have the accelerated warm up until the valve on the uim, next to the intercooler, and behind the bac valve broke so I just bypassed it straight from the uim manifold nipple to the interooler pipe.
Anyway, I start the car up after it sits over night and fires up to 500 rpms, slowly rising to maybe 700 for a second then it starts to drop, maybe die if I don't gas it up to keep it idling. I'd like to get it to idle right without dying so I can start the car up to warm it up while I am getting ready to leave.
On a side note, I have some bad voltage ...13.8/13.9 at idle, then to 13.6 after the car warms up. This is with no accessories on. The alternator is a rewired s5 model. Battery is new. I have just replaced because the other battery died after half a year of use. If I get below 750 rpms with some accessories like the a/c or if I am using the brakes, the car will lose voltage and want to die. These readings are coming from the greddy turbo timer, which seems to read lower sometimes than direct voltage reading from the battery. If the turbo timer is seeing less voltage than actual voltage, and the turbo timer reads the ecu, could the ecu also be seeing this low voltage and want to die? ...seems like a problem in the ecu or wiring maybe?
Either way, this is an old on going problem I have just usually delt with. Another one is hesitation/stuttering when the car get's around 13.4 volts or lower. I wanna say it has something to do with the ecu reading this low voltage and it effects my ignition, timing, fuel pump, etc.
Any input? I plan on taking it to a rotary doctor anyway, because I am tired of trying to solve this gremlin. But, I am willing to take a final stab at it.
Anyway, I start the car up after it sits over night and fires up to 500 rpms, slowly rising to maybe 700 for a second then it starts to drop, maybe die if I don't gas it up to keep it idling. I'd like to get it to idle right without dying so I can start the car up to warm it up while I am getting ready to leave.
On a side note, I have some bad voltage ...13.8/13.9 at idle, then to 13.6 after the car warms up. This is with no accessories on. The alternator is a rewired s5 model. Battery is new. I have just replaced because the other battery died after half a year of use. If I get below 750 rpms with some accessories like the a/c or if I am using the brakes, the car will lose voltage and want to die. These readings are coming from the greddy turbo timer, which seems to read lower sometimes than direct voltage reading from the battery. If the turbo timer is seeing less voltage than actual voltage, and the turbo timer reads the ecu, could the ecu also be seeing this low voltage and want to die? ...seems like a problem in the ecu or wiring maybe?
Either way, this is an old on going problem I have just usually delt with. Another one is hesitation/stuttering when the car get's around 13.4 volts or lower. I wanna say it has something to do with the ecu reading this low voltage and it effects my ignition, timing, fuel pump, etc.
Any input? I plan on taking it to a rotary doctor anyway, because I am tired of trying to solve this gremlin. But, I am willing to take a final stab at it.
06-16-2005, 01:32 PM
#2
Senior Member
Join Date: Feb 2004
Location: Orange Park FL
Posts: 363
Quick voltage test:
Engine running, headlights & heater fan on high:
Alternator post to alternator frame = 13.5-14 volts (verifies the alternator output)
alternator post to battery (+) = 0 volts (verifies the primary + wire)
alternator frame to battery (-) = 0 volts (verifies the primary ground)
Turn off the motor, but leave the lights on.
Battery (+) to battery (-) = ~12.5 volts and holds steady. (verifies battery)
Engine running, headlights & heater fan on high:
Alternator post to alternator frame = 13.5-14 volts (verifies the alternator output)
alternator post to battery (+) = 0 volts (verifies the primary + wire)
alternator frame to battery (-) = 0 volts (verifies the primary ground)
Turn off the motor, but leave the lights on.
Battery (+) to battery (-) = ~12.5 volts and holds steady. (verifies battery)
06-21-2005, 05:59 PM
#7
Senior Member
Thread Starter
Join Date: Nov 2003
Posts: 227
starting problem - mechanic added a relay so the starter sees voltage sooner
idle problem - bac valve clip had a bad wire, he put on a new clip and messed with the idle adjustments
stuttering - might be fuel pressure, gonna try tomorrow
ugh - yall dissappoint me
idle problem - bac valve clip had a bad wire, he put on a new clip and messed with the idle adjustments
stuttering - might be fuel pressure, gonna try tomorrow
ugh - yall dissappoint me
06-22-2005, 11:32 AM
#8
Senior Member
Join Date: Feb 2004
Location: Orange Park FL
Posts: 363
First: You said you piped the AWS circuit directly from the IC to the UIM.
That alone should have pushed you idle WAY UP.
Since you idle is slow, I have to assume some other adjustments were made to slow it back down, or the AWS circuit is plugged.
Second: Turbo timers are normally wired in at the ignition switch so they get their voltage reference directly from the main battery fuse.
Some timer voltmeters are not as accurate as others, but most are pretty close.
Third: If the BAC lets the idle fall below 700, the engine torque drops off a cliff and any load will stall it.
If the BAC is bad (or removed) you generally have to set the idle hard stops & air bleeds to 1000-1100RPM to get enough torque to keep from stalling.
So - what do you want for free?
That alone should have pushed you idle WAY UP.
Since you idle is slow, I have to assume some other adjustments were made to slow it back down, or the AWS circuit is plugged.
Second: Turbo timers are normally wired in at the ignition switch so they get their voltage reference directly from the main battery fuse.
Some timer voltmeters are not as accurate as others, but most are pretty close.
Third: If the BAC lets the idle fall below 700, the engine torque drops off a cliff and any load will stall it.
If the BAC is bad (or removed) you generally have to set the idle hard stops & air bleeds to 1000-1100RPM to get enough torque to keep from stalling.
So - what do you want for free?
06-22-2005, 12:09 PM
#9
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Thread Starter
Join Date: Nov 2003
Posts: 227
A cookie, but I'm glad you took the time respond. I am just shocked that in 5 days on 3 highly visited rx7 forums, you were the only one the had a comment.
Idle has never been above 1500 rpms with a properly set TPS, so maybe I misrepresented what the situation was there. The 3000 rpm startup valve broke, so I bypassed it ...shouldn't effect idle.
Yeah, I found out the turbo timer part yesterday. It's a Greddy meter, hopefully its accurate ...which means maybe I should consult the connections at the fuse.
I'm aware about the BAc issue, but I obviously only noticed that everything was connected ...not how well it was connected or wired.
Idle has never been above 1500 rpms with a properly set TPS, so maybe I misrepresented what the situation was there. The 3000 rpm startup valve broke, so I bypassed it ...shouldn't effect idle.
Yeah, I found out the turbo timer part yesterday. It's a Greddy meter, hopefully its accurate ...which means maybe I should consult the connections at the fuse.
I'm aware about the BAc issue, but I obviously only noticed that everything was connected ...not how well it was connected or wired.
06-22-2005, 12:42 PM
#10
Senior Member
Join Date: Feb 2004
Location: Orange Park FL
Posts: 363
[quote name='sureshot' date='Jun 16 2005, 02:32 PM']Quick voltage test:
Engine running, headlights & heater fan on high:
Alternator post to alternator frame = 13.5-14 volts (verifies the alternator output)
alternator post to battery (+) = 0 volts (verifies the primary + wire)
alternator frame to battery (-) = 0 volts (verifies the primary ground)
Turn off the motor, but leave the lights on.
Battery (+) to battery (-) = ~12.5 volts and holds steady. (verifies battery)
[/quote]
Here is why the above can be helpful.
High current wires can look perfect, but after 17 years corrosion can happen under the insulation.
The only clue is a voltage drop when they are under load, or some unusual warmth near the connections.
Engine running, headlights & heater fan on high:
Alternator post to alternator frame = 13.5-14 volts (verifies the alternator output)
alternator post to battery (+) = 0 volts (verifies the primary + wire)
alternator frame to battery (-) = 0 volts (verifies the primary ground)
Turn off the motor, but leave the lights on.
Battery (+) to battery (-) = ~12.5 volts and holds steady. (verifies battery)
[snapback]726234[/snapback]
[/quote]
Here is why the above can be helpful.
High current wires can look perfect, but after 17 years corrosion can happen under the insulation.
The only clue is a voltage drop when they are under load, or some unusual warmth near the connections.