EGR remova : DTC 27 , please help with resistor question...
06-06-2009, 05:47 PM
#1
Registered User
Thread Starter
Join Date: Mar 2000
Location: Eastsiiiiide , NH, USA
Posts: 112
EGR remova : DTC 27 , please help with resistor question...
I have searched my way through this forum 15 times, all the suggestions that come up I have tried and it's not helping me much but there may be some logic as to why...
car in question is 95 OBDI Formula , basically stock , recently I have removed AIR and EGR systems while I pulled the heads and it runs great, but when the check engine light comes up (DTC 27) the fans of course kick in etc...
- this happens WITH the solenoid still plugged in (and vacuum ports capped off). Not always, usually only after 20-30 minutes of slow driving, or after slowing down on the highway.
- if I unplug the solenoid the code happens immediately, within 1 minute or so.
- this used to happen BEFORE I removed EGR as well, so I thought it was a bad solenoid and figured I would just remove it with a help of a resistor.
- I measured the resistance of my "possibly bad" solenoid and it's 40ohms , I can't find a similar resistor but I have 37ohms and 47ohms , with 37 in there I still get the code, I have not tried the 47 yet...
am I using the right type of resistor btw? I shoved one of these in there (not the same exact one as pictured, but 37ohm one from radioshack).
does anyone know what the resistance should be? since my solenoid is questionable I'm not sure how to confirm the proper resistance.
also, is it guaranteed that EGR system with a good/new solenoid and capped off ports would trick the computer into thinking everything is fine? I'd rather buy a new solenoid than to get the ECM reprogrammed.
car in question is 95 OBDI Formula , basically stock , recently I have removed AIR and EGR systems while I pulled the heads and it runs great, but when the check engine light comes up (DTC 27) the fans of course kick in etc...
- this happens WITH the solenoid still plugged in (and vacuum ports capped off). Not always, usually only after 20-30 minutes of slow driving, or after slowing down on the highway.
- if I unplug the solenoid the code happens immediately, within 1 minute or so.
- this used to happen BEFORE I removed EGR as well, so I thought it was a bad solenoid and figured I would just remove it with a help of a resistor.
- I measured the resistance of my "possibly bad" solenoid and it's 40ohms , I can't find a similar resistor but I have 37ohms and 47ohms , with 37 in there I still get the code, I have not tried the 47 yet...
am I using the right type of resistor btw? I shoved one of these in there (not the same exact one as pictured, but 37ohm one from radioshack).
does anyone know what the resistance should be? since my solenoid is questionable I'm not sure how to confirm the proper resistance.
also, is it guaranteed that EGR system with a good/new solenoid and capped off ports would trick the computer into thinking everything is fine? I'd rather buy a new solenoid than to get the ECM reprogrammed.
06-07-2009, 07:47 AM
#4
Guest
Join Date: Sep 2004
Posts: 0
What you will accomplish with a relay coil is a lot more than you have accomplished so far.
The solenoid you are replacing is a coil. A resistor is not good enough to allow the PCM to sink all the current. So simply replace one coil with another. How do you think we get the led 3rd tail lights to work and not deactivate the ABS and cruise control??? With a relay!!!!
The solenoid you are replacing is a coil. A resistor is not good enough to allow the PCM to sink all the current. So simply replace one coil with another. How do you think we get the led 3rd tail lights to work and not deactivate the ABS and cruise control??? With a relay!!!!
06-07-2009, 10:29 AM
#5
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,646
The EVAP and EGR solenoid diagnostic is only looking for a complete circuit. It wants to see ~B+ (12-15V) when the solenoid is not activated and "close to" 0V when it is activated. All you should need is a resistor in the 150-200 ohm range. The larger value reduces the "watt" rating of the resistor.
Look at the "skip-shift eliminator".... a 2,000 ohm resistor works just fine, even though the resistance of the skip-shift solenoid is appreciably smaller. The diagnostic on the EVAP or EGR solenoid and the skip-shift solenoids is identical.
The problem with exactly matching the solenoid resistance is the power in the resistor. The solenoids I've tested were closer to 15 ohms, meaning you'll see about 1 amp on the circuit. A 15 ohm resistor would have to be rated in excess of 15 watts (I^2R). A larger resistor can have a much lower rating - e.g. 1 watt.
Look at the "skip-shift eliminator".... a 2,000 ohm resistor works just fine, even though the resistance of the skip-shift solenoid is appreciably smaller. The diagnostic on the EVAP or EGR solenoid and the skip-shift solenoids is identical.
The problem with exactly matching the solenoid resistance is the power in the resistor. The solenoids I've tested were closer to 15 ohms, meaning you'll see about 1 amp on the circuit. A 15 ohm resistor would have to be rated in excess of 15 watts (I^2R). A larger resistor can have a much lower rating - e.g. 1 watt.
06-08-2009, 07:29 PM
#6
Registered User
Thread Starter
Join Date: Mar 2000
Location: Eastsiiiiide , NH, USA
Posts: 112
What you will accomplish with a relay coil is a lot more than you have accomplished so far.
The solenoid you are replacing is a coil. A resistor is not good enough to allow the PCM to sink all the current. So simply replace one coil with another. How do you think we get the led 3rd tail lights to work and not deactivate the ABS and cruise control??? With a relay!!!!
The solenoid you are replacing is a coil. A resistor is not good enough to allow the PCM to sink all the current. So simply replace one coil with another. How do you think we get the led 3rd tail lights to work and not deactivate the ABS and cruise control??? With a relay!!!!
I would never think a 3rd LED tail light would deactivate ABS either but I'm sure that happens, you have to see some strangeness in that statement though right? lol
there's a reason why I prefer 3rdgens and older muscle cars
Last edited by Zrout; 06-08-2009 at 07:31 PM.
06-08-2009, 07:30 PM
#7
Registered User
Thread Starter
Join Date: Mar 2000
Location: Eastsiiiiide , NH, USA
Posts: 112
The EVAP and EGR solenoid diagnostic is only looking for a complete circuit. It wants to see ~B+ (12-15V) when the solenoid is not activated and "close to" 0V when it is activated. All you should need is a resistor in the 150-200 ohm range. The larger value reduces the "watt" rating of the resistor.
Look at the "skip-shift eliminator".... a 2,000 ohm resistor works just fine, even though the resistance of the skip-shift solenoid is appreciably smaller. The diagnostic on the EVAP or EGR solenoid and the skip-shift solenoids is identical.
The problem with exactly matching the solenoid resistance is the power in the resistor. The solenoids I've tested were closer to 15 ohms, meaning you'll see about 1 amp on the circuit. A 15 ohm resistor would have to be rated in excess of 15 watts (I^2R). A larger resistor can have a much lower rating - e.g. 1 watt.
Look at the "skip-shift eliminator".... a 2,000 ohm resistor works just fine, even though the resistance of the skip-shift solenoid is appreciably smaller. The diagnostic on the EVAP or EGR solenoid and the skip-shift solenoids is identical.
The problem with exactly matching the solenoid resistance is the power in the resistor. The solenoids I've tested were closer to 15 ohms, meaning you'll see about 1 amp on the circuit. A 15 ohm resistor would have to be rated in excess of 15 watts (I^2R). A larger resistor can have a much lower rating - e.g. 1 watt.
ok, I will try again with a 150-200ohm resistor. Thank you for the input.
06-08-2009, 10:11 PM
#8
Registered User
Join Date: Dec 1969
Location: Little Rock, AR
Posts: 27,709
In this case, the relay is not used in the conventional sense. It is only used for the coil in it (to provide resistance and dissipate heat that a conventional resistor has trouble doing without overheating). The relay contacts are not even used.
Thread
Thread Starter
Forum
Replies
Last Post