i have a 93 regal that misfires - at least that's what i assume it's called when i hear tail pipe explosions and smell as if you're lighting matches. no smoke. the engine rpm varies a lot and sometimes cuts off. the whole car is shaking like one of those adventure rides!

it has done this twice in the past couple of weeks when i start it after a few days of sitting there. the strange thing is that it goes away after a few minutes of running or at the next start after it cuts off. so it's driving nicely as usually after the initial fits. it's not doing this while driving at least not yet.

last oil change was about 400 miles and about 2 months back.

i pulled the wires going to the coils and it's sparking so they appear fine. it's the same gas tank on both occasions (more than half used) - not driving the regal more than a few miles a week.

so i'm wondering is it dirt in the gas or a problem with the gas filter/pump? or could it be the oxygen sensor or smth else?

3.8 engine, 151000 miles - blinks code 17 when connected to A/B.

any help is appreciated!

Do you have any DTC's stored? 1993 can be checked by jumping ALDL terminal A&B to get the codes. Let us know the mileage of car also.

151000 miles - blinks code 17 camshaft. i wonder could it be "partly" broken so that it works most times but then some times the computer loses track and tries to go into failsafe?

BTW - when i plugged the AB paperclip and turned the key (not crank) the big fans in front of the engine started to rotate wildly and after disconnecting them (pulled the 2 relays) there was still a constant clicking coming from the driver's side of the engine (about where the ABS and horn are). any idea why? all this stopped once i pulled the paperclip.

Code 17 according to my book is; PCM did not detect any spark reference pulses within 240 fuel control reference pulses (80 crank revolutions) while engine was running below 1200 RPM. Spark Reference Circuit. ECM fault crank position sensor circuit.

BTW, fans will run and relays will click when in the diagnostic mode.

Code 17 according to my book is; PCM did not detect any spark reference pulses within 240 fuel control reference pulses (80 crank revolutions) while engine was running below 1200 RPM. Spark Reference Circuit. ECM fault crank position sensor circuit.

BTW, fans will run and relays will click when in the diagnostic mode.

hmm i used the haynes book for the code.

so what exactly do i need to check and how?

Does your car have a 3.1 or 3.8 engine?

Does your car have a 3.1 or 3.8 engine?
3.8

I also show code 17 as a camshaft position sensor circuit problem. The ECM uses signals from the cam and crank sensors to adjust spark timing. Your problem could be either the cam position sensor itself, the wiring to it, or the magnet in the cam gear that the sensor picks up it signal from.

This can also be the crank position sensor (CKPS), or the ICM is failing to buffer the spark reference signal to the PCM. During normal operation, the PCM uses the spark reference signal to control ignition timing until the engine speed exceeds 1200 rpm, at which time the fuel control reference signal is used. If the window on the harmonic balancer is interfacing with the 18x Hall-effect switch, the ignition control module will ground the spark reference signal. When conditions exist for setting DTC 17, the fuel reference is used by the PCM to control ignition timing advance. This condition will cause module mode to be used for timing advance below 400 rpm and IC ignition timing to be degraded below 1200 rpm. If connections and harness are OK, try checking voltage on CKT 647 (terminal C - LT BLU/BLK) with a DVM while moving the related wiring harness and terminals with engine idling. This may help isolate the location of the malfunction.


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thanks for all your replies!

next time it does this i'll check terminal 647. it reminds me of the TPS problem i had some time ago - when the sensor had a "bad" spot and it would only have the issue sometimes but work fine most of the time.

i've also found out that Murray's doesnt loan those Actron scanners anymore - for some odd reason... too bad they did help a lot.

i've been quite busy for a while but tonight i located the camshaft sensor and it's a pain to get to so i'm thinking of alternatives.

the car cuts off when idling at a light (or in the parking lot) but works fine when driving. it also surges sometimes close to 2000rpm then back to 800 or so as if it's randomly getting too little then too much air or fuel - also in idle mode only. also in idle if i rev the engine it sometimes stalls after the rpms come back down.. could it be the knock sensor or the IAC? just asking because i read the knock sensor causes the ECM to retard the knock and even cause rough idle if broken. same goes for the IAC... and they are both much easier to replace or test!

how do i test the knock sensor?

can i clean the IAC without removing it? i'd like to reuse it after removing because it's 60 bucks... is it safe to remove it or will it break considering the car is 15 years old?

thanks!

ok i got a spray can of throttle/carb cleaner and one of silicone spray for 7 bucks total. took out the IAC (a pain!) cleaned with carb cleaner on the pintle and the inside of the throttle body, then finished off with a spray of silicone. i also checked the resistance of the coils (55 ohms in AB and CD). at first i forgot to reset the computer and the car wasnt really starting. then i did the 5 second on/10 second off and it started just fine.

BTW to put the screws back in i tied them with beading wire (or other wire) and secured around the throttle body or wires in the area. this way i made sure they dont fall off if i dont screw them in properly.

the test drive was very promising. no more idle surging, just barely at the beginning when the engine wasnt warmed up. the idle is pretty much constant around 900 or so rpm even at the longer stops at lights. it's quite amazing because even though i did soil a lot of cotton swabs, it didnt look like a lot of buildup.

i hope that solved it...

NOT SOLVED... it died again when i stopped at a light. the engine just stops, no noises or vibration, its as if i turned off the ignition - and it can happen 5 minutes into the drive or just before i reach my destination 40 minutes later. started up rightaway as usually...

so i decided to replace the $2.99 PCV valve. old one looks full of gunk and barely rattles while the new one is moving a lot more inside. the test drive was fine (as usually) and the idle is stable around 900. now remains to be seen in day to day traffic...

if that doesnt doesnt work i read somewhere there's a re-learn procedure (disconnect battery and retrain car like here http://www.v6z24.com/howto/idlerelearn )... or adjusting the minimum air rate screw for the idle - although thats probably not the case.

if you have any other ideas of what to test i'd really appreciate it!

not fixed... stopping got worse. it's actually stalling just when i get close to a red light that turns green sometimes. so i have to stop all the way, park and then restart with ppl assuming i'd accelerate. almost got rearended :(

i removed the MAF connector and immediately got SES light on. codes are 34 (maf sensor) and 26 (quad driver) - i assume it was caused by the voltage surge when i removed the MAF.

the idle appeared to improve with it unplugged! when i plugged the connector back into the MAF the engine started choking. after revving it a bit it got back to around 1000 rpms but it wasnt an even idle.

i'm planning to change the Crankshaft position sensor first and if that doesnt do it then it's the more expensive MAF...

any other suggestions? please any help is appreciated as driving the car is becoming dangerous with all the stalls at lights.

access to the sensor / balancer is quite easy even without removing the wheel, just turning it right. however it's not a 28mm socket as some books say. the problem is that i cant unscrew it - the engine rotates.

i decided to let a shop exchange the crankshaft sensor for about $140. hopefully that will do it.

it worked perfectly with the new crankshaft sensor! for a few days... tues/wed/thurs/fri about 20 miles each day but now friday evening it started doing it again on the way home and in the parking when i got there. after i let it sit for half an hour i checked the codes and 17 was there again.

started it up again and it died rightaway. then started again and it ran - rough and vibrating.

so i removed the battery for a few minutes and the car started fine. it was rough for a few seconds (idle re-learn...?) but then it settled. no code 17 anymore and the test drive was fine. it idled 15 or so minutes without issues.

is it possible that the spark plugs create this code 17 error? or possibly were they fouled by driving when the sensor was bad and misfiring? maybe the IAC is bad and doesnt allow enough air which chokes the engine and causes it to think its due to the spark reference? did the shop screw me over and not change the sensor (cant see due to the balancer and the sensor protector) and put in a bad crankshaft sensor?

if not - what can give code 17 on this type of car? and how come removing the battery helps?

i would really appreciate any help - i'm at a complete loss. this only started in july when i posted and got really bad this monday when it stalled 6 times in a day! please help!

i tested the EGR with 9 Volt battery (A+ and B, C, D on -) it clicked on all. coil values pretty close to this post: http://www.automotiveforums.com/vbulletin/showpost.php?p=4914488&postcount=2

then I checked the coils and they are OK (between 5-8Kohms high voltage and 1.5 ohms low voltage side).

i took the ignition module to Murray's for testing. it tested all green. however the car isnt starting anymore now, its just turning over... i hear the pump pressurizing the system and the exhaust starts smelling like pure gas after a few tries. there is no spark on the coils while cranking (removed one of the boots at a time to see if there's spark)... the computer only has code 12 which is "OK"...

this is getting better and better.

i took the ignition module back to murray's and they tested it again - it was always good.

turns out the ignition module was not grounding to the plate on which it's screwed on. there was lots of oxide and some dirt on both the ignition module back and the ground plate behind it (i think it's also a heat spreader). i used sand paper to clean and then put petroleum jelly on the bottom to avoid new oxide forming. also put petroleum jelly on the low voltage and high voltage connectors of the coils. the car started rightaway.

however now that the car is running i don't think my initial issue - idle stalling - is fixed. haven't had it yet but it would be too good to be true - that the ignition module was not getting proper ground and thats why it would cut off and not supply the computer with spark reference...

still planning to do a EGR valve cleanup and a vacuum check. never done either so wish me luck...

as usually any input is appreciated on what to test next - but i'm assuming that either ppl don't care about this thread anymore or those who know the car stuff are all on vacation or too busy to check the forum.

i just discovered another symptom! don't know if it's related but...

if i brake very hard the rpms go down slightly while at idle. so if i'm in park with the engine warmed up after test drive and 900rpm idle, then i press the brake pedal very hard twice in a row the engine rpm goes down to 700 (i'd say) and i can feel a hesitation. it doesn't die and goes right back up to normal, but it's just odd because i never noticed/cared about it before.

is this an indication of a power brake issue, a vacuum leak or just a normal way of reacting because i'm using up the available engine vacuum quickly?

just to mention the idle stall happens mostly while sitting at a light, just barely holding the brake.

the car ran fine today but i pulled code 17 from the computer again. i assume this is another stall waiting to happen... i dont understand what else than what i've already checked/changed can cause this code. Knock sensor? vacuum? camshaft sensor?