FAQ: Rough / Slow / No Start - Symptoms, Causes, Solutions

I don't know a whole lot about diagnosis(i don't know a whole lot about anything for that matter) but from experience,don't just assume the "new" computer is good. and what happened to me,make sure the new computer has a eprom chip for a "SUPERCHARGED" vehicle and not a N/A vehicle....I'm guessing he checked the crank position sensor too right?

robotennis61 wrote:

I don't know a whole lot about diagnosis(i don't know a whole lot about anything for that matter) but from experience,don't just assume the "new" computer is good. and what happened to me,make sure the new computer has a eprom chip for a "SUPERCHARGED" vehicle and not a N/A vehicle....I'm guessing he checked the crank position sensor too right?

I'll clarify the sensor issue when I talk to him, I know he replaced one and I assume he at least checked the other. I'll find out which is which. I was sort of blindsided by this because I expected him to call to say "Come pick it up!" and instead I got the whole rundown I detailed earlier, so I'm struggling to recall exactly what he told me.

Suggest your mechanic replace the crank position sensor whether it tests good or not.

Explanation:

The crank sensor (CKP) - That is a "hall effect" sensor and has the nasty habit of failing warm. That is the car will run, you'll park it for 1/2 hour to 2 hours and it won't start at all.

The crank position sensor is a PITA to change, requires pulling the harmonic balancer - which admittedly is not a big deal if you remove the fornt wheel on passnger side and you have the GM puller or the right bolts to adapt a universal puller (because without the right puller usually you rip the rubber in the balancer. If that happens don't cheap out get a good GM or NAPA harmonic balancer not the cheapest you can find --- even a used OE one is better than the cheap aftermarket ones (the rubber is very different in the OE one).

Anyway, the key problem with the crank sensor failure is that the crank sensor will often test good when it is not... and your failure pattern suggests crank sensor failure. The crank sensor does not read a magnet, it senses the passing of the teeth on a 'cooky cutter' that is riveted into the backside of the harmonic balancer.

I reckon your problem is in the CKP or the wiring to it, need to check the harness for physical damage and loosened terminals (male and female off the wires) in a few key places:

1) at the CKP by the harmonic balancer
2) at the large connector at the firewall, there have been many posts about the wires in the corners busting for no apparent reason
2) at the large connector to the ignition module under the coil pack

By the way the *cam* sensor is a lot easier to get to. It is a little coil that reads a magnet. I changed mine last year (for maintenance). You can change it one-handed if you have a sense of humor. I strongly suspect that is the one your mech changed.

Final item - when you get a replacement CKP, don't cheap out. Get a Delphi or Delco, don't want to have to replace it again.

Post an update please when you know more.

Albertj

To add to albert's explanation....If you can, check to see if you have spark while cranking. If the Crank Sensor is bad, you will not have spark while cranking.

Also, if you're planning on seeing your mechanic again, make sure he checks for main power at the Ignition Control Module, CKP and CMP. But, not just for 12V, Amps too. I've seen Ignition Switches go bad and do exactly what has happened to you. The same thing happened to me.....I had spark, I had fuel, and I had Injector Pulse, but there wasn't enough current to operate everything properly.

Abaddon wrote:

To add to albert's explanation....If you can, check to see if you have spark while cranking. If the Crank Sensor is bad, you will not have spark while cranking.

Also, if you're planning on seeing your mechanic again, make sure he checks for main power at the Ignition Control Module, CKP and CMP. But, not just for 12V, Amps too. I've seen Ignition Switches go bad and do exactly what has happened to you. The same thing happened to me.....I had spark, I had fuel, and I had Injector Pulse, but there wasn't enough current to operate everything properly.

MMM,,, yeah I forgot about the ignition switch. The switch and the lock separate, just have to take off the column clamshell to replace the switch. A bum ignition switch also will not set a code. Great catch and easier than the CKP.

If your mechanic has a scanner (not just a code reader) he should be able to hook it up and see whether the crank and cam sensors are sending pulses. If so, I'd then check the ignition switch.

At the age and mileage of your car, the CKP and ignition switch are kind of "due" for replacement. Nearing the 150K mile engineering/design lifetime. Just saying.

Thanks Scott

Albert

Might want to consider checking the temperature control sensor.Many times the TCS will not set codes and contribute to the non-start issue.

First of all, your mechanic seems to be guessing instead of diagnosing. Any one could misdiagnose a problem, but to go from timing chain to ecm to sensors is an expensive trial and error process. Hopefully he will not charge you for his incompetence.

Easiest way to check for a faulty ignition switch on this car, probe fuses in left side dash fuse box. Some fuses that should have voltage with key in run position will not. Specifially the fuel injector fuse,should be hot during run and crank.

If this condition exists, remove lower dash panel and unbolt fuse box to gain access to ignition switch wires entering the fuse box. Probe the large pink wires to find which one has no power. Then probe all large pink wires to find one that is hot in run and crank. At this point you can jump the dead pink wire to one that functions properly.

Assuming your mechanic installed all other parts correctly the car should start and run. If not, repair whatever else he f'd up.

After car is running properly, install new ignition switch. If these conditions exist then ignition switch was most likely your only problem. I would not invest in new switch until you are sure the timing chain, ecm and other parts installed are working properly. Good luck.

60kriv wrote:

Might want to consider checking the temperature control sensor.Many times the TCS will not set codes and contribute to the non-start issue.

To which "temperature sensor" are you referring? The IAT (Intake Air Temp)? This would cause misfires, horrible gas mileage, or a lean/rich condition, not a no start condition.

as for bigdave's explanation.....If the Ignition Switch were bad enough to where it was killing power to almost everything, the DIC would more than likely not light up.....meaning that when you turn the key forward to the RUN position, no MIL or trouble lights would illuminate (diagnostic check mode). This happens rarely, but it is a symptom of a faulty Ignition Switch. Usually (on a Buick), when it goes, this no start-no MIL-no codes issue is the only symptom. I don't know why this is, but I've yet to see a Buick Ignition Switch totally fry like that.

Scott, I didn't see any mention of power being killed to almost everything. On the 95 Riv, there are several wires coming off the ignition switch.The large pink ones supply power to different points. Some are hot in run and crank.Not only is it possoble to fry one of these circuits and not the others, but I have experienced it first hand. I had a 95 Riv that had fuel pressure at port and spark but would not start. I probed fi fuse and had no power. Also found no power to approx 6 other fuses. I proceded with steps mentioned in my earlier post and problem solved. So, this situation is possible and should be considered before anymore parts are thrown at this guys car.

I didn't say it can't happen dave. If you read, I said it is possible, just rare. I wasn't saying you're wrong man. and if you read my post above that, I had the same scenario as you on my car

No problem Scott, I just thought I'd share my experience before his mechanic sells him a fuel pump and muffler bearings.

bigdave wrote:

No problem Scott, I just thought I'd share my experience before his mechanic sells him a fuel pump and muffler bearings.

Ain't that the truth? It's a shame....I'm ashamed of my own kind!

bigdave wrote:

No problem Scott, I just thought I'd share my experience before his mechanic sells him a fuel pump and muffler bearings.

Oh jeez, do you think it could be muffler bearings? That sounds expensive!

Kidding.

Thanks for all your help, I've relayed all your ideas to the mechanic and I'll be back in touch with any updates or hopefully a solution.

bigdave wrote:

No problem Scott, I just thought I'd share my experience before his mechanic sells him a fuel pump and muffler bearings.

that's the funniest damn thing I've heard all day! lolz

maybe it good be the headlight fluid is to low...hahaha..

bigdave wrote:

First of all, your mechanic seems to be guessing instead of diagnosing. Any one could misdiagnose a problem, but to go from timing chain to ecm to sensors is an expensive trial and error process. Hopefully he will not charge you for his incompetence.

Easiest way to check for a faulty ignition switch on this car, probe fuses in left side dash fuse box. Some fuses that should have voltage with key in run position will not. Specifially the fuel injector fuse,should be hot during run and crank.

If this condition exists, remove lower dash panel and unbolt fuse box to gain access to ignition switch wires entering the fuse box. Probe the large pink wires to find which one has no power. Then probe all large pink wires to find one that is hot in run and crank. At this point you can jump the dead pink wire to one that functions properly.

Assuming your mechanic installed all other parts correctly the car should start and run. If not, repair whatever else he f'd up.

After car is running properly, install new ignition switch. If these conditions exist then ignition switch was most likely your only problem. I would not invest in new switch until you are sure the timing chain, ecm and other parts installed are working properly. Good luck.

Great post.

Also, remember it would be nice to un-do those splices after you replace the ignition switch.

By the way at your car's age and mileage it would not be unusual for two or three of these basic systems (ignition switch, CKP...) to fail at about the same time. Bigdave and Scott laid out nice diagnostics, I'm sure with some patience you'll get it fixed once and done (at least be rid of this problem for another 150K miles).

Albertj

Thanks again for all the helpful info, and here's a quick update.

I relayed all your suggestions to the mechanic and he left me a phone message on Friday. He said they tried some of them, others had already been tried, and that he now had replaced the "other" sensor (don't know which he did the first go-round, cam or crank, but now they've both been done) and that resolved the "out of sync" issue. But the car still won't start because four injectors aren't firing.

That's all I could get from the message and he's been closed for the holiday. I'll speak to him later today.

ddonohue wrote:

Thanks again for all the helpful info, and here's a quick update.

I relayed all your suggestions to the mechanic and he left me a phone message on Friday. He said they tried some of them, others had already been tried, and that he now had replaced the "other" sensor (don't know which he did the first go-round, cam or crank, but now they've both been done) and that resolved the "out of sync" issue. But the car still won't start because four injectors aren't firing.

That's all I could get from the message and he's been closed for the holiday. I'll speak to him later today.

wow! 4 injectors at once?

robotennis61 wrote:

ddonohue wrote:

Thanks again for all the helpful info, and here's a quick update.

I relayed all your suggestions to the mechanic and he left me a phone message on Friday. He said they tried some of them, others had already been tried, and that he now had replaced the "other" sensor (don't know which he did the first go-round, cam or crank, but now they've both been done) and that resolved the "out of sync" issue. But the car still won't start because four injectors aren't firing.

That's all I could get from the message and he's been closed for the holiday. I'll speak to him later today.

wow! 4 injectors at once?

I suspect they will identify the four injectors, then work backwards from each to find damage to the wiring...


Albertj

Not quite sure where this post belongs but I have a 95 SC riviera and it wont start. I just got the battery tested/charged at auto zone and they say its fine. When I put the key in the car all the lights come on but when I turn it all I hear is a click noise. There is no crank and I don't think its the alternator because when I'm driving, the car doesn't cut off on me. However, when I get some one to jump my car it does turn on, but it wont start w/o a jump and like I said auto zone said the battery is fine. Does this mean its my starter that needs to be replaced? Is there any way to check for it? Thanks for any help. Sorry if its in the wrong section.

That is an odd one. I was ready to guess starter until you said it would start with a jump.

Are you jumping using the jump connector under the hood? If so, I'm thinking that might be a clue. Sounds like juice can get to the starter from there, but there's some fault between the battery and the starter preventing full power from making it through.

Yes! I am using the jump connector from under the hood when jumping the car. About a month and a half ago when we got all this snow I didn't drive my car for like 2 days and I tried to start it and came across this same issue. I got a jump and it started. After that the car started up and ran fine until about a week ago. When I would try and start it, sometimes it wouldn't start right away. I would have to turn the key several times w/ no crank and after so many tries it would start, sometimes 2-4 and one time over 10. Then, the other night it wouldn't start at all and my cousin gave me a jump and it started. I drove to the gas station cause I was on E and put some gas in w/o turning the car off to let it charge since we figured the battery must just be on its last leg even though it always came on I thought maybe it just didn't have enough juice to start the car. So after I got the gas I went to Acme and cut the car off, went inside for like 10 minutes and came back out. I had to turn the key 2 times and the car started. I tried to start it the following day, which was yesterday and it won't start like I said above.Now I did notice that after I got my battery charged at auto zone and I hooked it up and tried to start my car that when I would release the key after I tried to turn it on and heard the "click" under the hood I heard a similar click coming from what looks like a fuse box under my back seat adjacent from my battery. I couldn't get the cover completely off to see exactly where the clicking was coming from but I did see 3 fuses in the box and I checked all of them and they are fine.

RivieraRyan wrote:

Yes! I am using the jump connector from under the hood when jumping the car. About a month and a half ago when we got all this snow I didn't drive my car for like 2 days and I tried to start it and came across this same issue. I got a jump and it started. After that the car started up and ran fine until about a week ago. When I would try and start it, sometimes it wouldn't start right away. I would have to turn the key several times w/ no crank and after so many tries it would start, sometimes 2-4 and one time over 10. Then, the other night it wouldn't start at all and my cousin gave me a jump and it started. I drove to the gas station cause I was on E and put some gas in w/o turning the car off to let it charge since we figured the battery must just be on its last leg even though it always came on I thought maybe it just didn't have enough juice to start the car. So after I got the gas I went to Acme and cut the car off, went inside for like 10 minutes and came back out. I had to turn the key 2 times and the car started. I tried to start it the following day, which was yesterday and it won't start like I said above.Now I did notice that after I got my battery charged at auto zone and I hooked it up and tried to start my car that when I would release the key after I tried to turn it on and heard the "click" under the hood I heard a similar click coming from what looks like a fuse box under my back seat adjacent from my battery. I couldn't get the cover completely off to see exactly where the clicking was coming from but I did see 3 fuses in the box and I checked all of them and they are fine.

Very quickly:

Clicking comes either from relays or thermal breakers in the fuse boxes under the rear seat.

I have a bunch of questions and no answers... What do your battery cables look like? Are there any parts that are kinda fat, or where the plastic covering is split and there's a white or green powder showing? Do you have the battery with vent tubes that go thru the floor? Is it possible that your battery may have an internal fault or that your battery cables have corrosion that reduces their conductivity? Maybe you could post a picture of the battery/cables under the rear seat, and the area where the cable is connected (the power point) under the hood (where you jump the car); did you already disassembled and clean that connection at the power point? does your car have an aftermarket alarm system? is the battery more than 5 years old, and did the autozone folks test it to see what it's current CCA capacity is (I think the min spec is 480, the correct battery when new will be either 880 or 970 CCA)?

Do tell, please.

Albertj

Ok, so I was taking some pictures and video of my "battery area" and of me trying to start the car. In the midst of doing this I decided to check the fuses in the box connected to the positive battery cable and all of them were intact except for the 20 fuse that was in the slot of the ELC(electronic level control). I'm not sure if this was causing my problem or not so I went back to auto zone and replaced the fuse, but the car still wouldn't start so I figured maybe that fuse being blown was draining my battery. I went back to auto zone to get it recharged and when I got it back the lady "checked" it and said it was bad. She said the guy who gave it back to me yesterday and said "it was cool" probably just charged it and didn't check it. So I am going to get a new battery tomorrow morning but I am curious as to what effects that fuse has. Also, all my cables seem to be intact and fine. The lady also said the battery I currently have is not a vented battery and she is surprised that it has lasted so long already. I took the pics on my phone and will try to post them.