Out of ideas, Need Help Please, 700 Miles on new motor RT wont start.

[ACELLR8]

Myself and my viper-tech have been trying to figure out what the problem is on my 95 and are running out of ideas, any help or knowledge would be greatly appreciated!!

Here is the situation, I just had the motor totally rebuilt, top and bottom end. Car ran great for 700 miles. Went out last Friday for a drive got about 2 miles from the house and the car started back firing really bad and shooting big flames out the side pipes, car stalled. I pulled off to the side of the road, started it up, it started right up, drove another mile back towards home and it did the same thing after a few hundred yards. At this point I could get the car started, but it was running real rough unless I was in the gas at about 2500 RPM, then it was smooth with an occassional miss. Then I tried to let it idle it stalled and I really have not been able to get it to run for more than 10 seconds or so without it backfiring real bad and missing, consequently stalling. No check engine light ever came on during any of my problems too, thought that was strange.

Here is what Corrective actions I have done so far.
Check spark - Spark was ok! Changed coil packs anyway's, because I heard they fail when heated up. At this time put new plugs in again. Plug wires are new.
Check all wires and electrical connections - After doing a search and reading about bad wires at the wiring harness and cam sensor wire. Checked all wires pins to make sure none are pushed in.
Had my tech put his diagnostic computer on My tech came out to my house and put his diagnostic computer on and there was no codes, could not find any faults. I unplugged the computer when changing coil packs to reset everything, but no codes came up when I managed to get it started for a brief seconds afterwards.
Checked injectors One thing we did notice that was strange was the injectors only had power very intermitantly, maybe once out of every 12 or so key turns. For a stare and compare my 2001 had power on every key crank.
What controls the power on the injectors? We had ground the whole time, but power was not there always. The fuel pump was pumping, I could hear that. The plugs also seemed soaked with fuel, so it definitely seemed like fuel was getting there, but the problems with the injectors has me curious.

Any one else had strange problems like this? What are the chances the ECU is bad? Kind of sounds like a timing issue to me, but can't figure out what is causing it.

Any help would be appreciated! I am loosing sleep over this and don't want to have the car towed to the dealer as I don't feel to confident in any of my local dealers. Plus I want to get it running by Chucks BBQ.

Thanks!!

Ed

 

[monnieh]

do you have a Vec1 on the car?

 

[ACELLR8]

do you have a Vec1 on the car?

No it still has the stock ECU, original 95 one.

 

[Dave's Big Brakes]

Try a new computer, they do take a dump without showing codes

 

[Tom F&L GoR]

Have to read in the service manual for which ones, but sensors like the crank position sensor and the oil pressure sender for the ECU (not gauge) might cause this? (Had a crank sensor in a Jeep with problem that sounds like yours.) Without the signals, engine doesn't know it's spinning or where it is in the spin cycle. If you're lucky, you could swap the '95 parts for the 01 parts.

 

[3snakes]

if it is bvackfiring thru exhaust it is someting elec.

 

[dansauto]

f'ing geniuses on this site nowadays, Ed-I sent you a email give me a call.

 

[RED97GTS]

What is the fuel pressure?

 

[PaViper]

Ed, if you need an extra hand this weekend, let me know. I can at least lend moral support.
carmen

 

[Jack B]

Is it back-firing in the intake or exhaust?

 

[Viper Specialty]

recomend:

Try swapping out the Crank sensor with a friends Viper. Easy to swap, held in with one bolt on the passenger side, under the headers. if no change, try swapping the cam sensor too. Both of those sensors can cause EXACTLY what you are describing. I have a good used Crank sensor available, and can get you a new Cam sensor if need be.

In a nutshell, the ECU is getting "ghost signals" from the bad sensor(s), and is firing the injectors at the wrong time, OR, not firing them at all sometimes.

 

[Vic]

A problem that changes after warm-up could be heat related, like if the cam sensor sends good input back to the computer when its cold, but after warm-up, it gives bad info. That would make it start up ok, but then the problem occurs after a couple of minutes, when the sensor gets hot. Its best to put new sensors as a matter of good practice, rather than spend hours troubleshooting an intermittant problem.

I don't suppose the cam could shift position in relation to the crank, could it?

 

[Viper Specialty]

I don't suppose the cam could shift position in relation to the crank, could it?

Only if the timing chain skipped a few teeth... but that wont happen unless it is VERRRRRRRY poorly adjusted. Timing BELTS are known to do this, becuase they use auto-tensioners, and have "give" to them due to rubber construction. Chains are not known to do this without reason...

I am betting on this being either a crank or cam sensor myself...

 

[ACELLR8]

Is it back-firing in the intake or exhaust?

Now I can't get it started at all, maybe a brief second, as I am trying to start it, it will backfire in the exhaust or intake and sometimes both.

 

[ACELLR8]

recomend:

Try swapping out the Crank sensor with a friends Viper. Easy to swap, held in with one bolt on the passenger side, under the headers. if no change, try swapping the cam sensor too. Both of those sensors can cause EXACTLY what you are describing. I have a good used Crank sensor available, and can get you a new Cam sensor if need be.

In a nutshell, the ECU is getting "ghost signals" from the bad sensor(s), and is firing the injectors at the wrong time, OR, not firing them at all sometimes.

My mechanic ordered a cam sensor and we are going to try that tonight. We are also suspicious the cam bushing may have spun out or something and threw the cam degree out. Before he tears the front of the motor apart we want to eliminate the small and simpler things. He is gonna do a compression test and leakdown test to, to see if the cam is still positioned right.


Thanks everyone for your help. I will update as I find out, in case anyone else experiences this.

Ed

 

[ACELLR8]

Thanks all for the input. My mechanic figured out the problem today over lunch.

Turned out it was a bad cam sensor. Replaced sensor, fired right up and is now running smoothly.

Ed

 

[99 R/T 10]

Good to hear it was something simple, what does something like that cost? Just curious,

 

[ACELLR8]

Good to hear it was something simple, what does something like that cost? Just curious,

Yeah I was pretty thrilled. He did not charge me for the part, so I am not a 100% sure, but I think they are around $70.

I guess it appears it was nothing to do with the rebuild just coincidence that it failed not long after engine rebuild, I guess I could have replaced them.

Ed

 

[2BADD 4U]

I don't suppose the cam could shift position in relation to the crank, could it?

Only if the timing chain skipped a few teeth... but that wont happen unless it is VERRRRRRRY poorly adjusted. Timing BELTS are known to do this, becuase they use auto-tensioners, and have "give" to them due to rubber construction. Chains are not known to do this without reason...

I am betting on this being either a crank or cam sensor myself...

Nice Call Daniel!!!

Ed,glad to see your back in business!!!

See you on Sat!

Dave

 

[PaViper]

Glad to see you got it figured out Ed, see ya Sat..
Carmen

 

[RedEnuf93]

Good news ED!
We'll see the Yellow Banana on our convoy!!!!!

Lauri

 

[ACELLR8]

Here is an update on this one for everyone that was helping me and may be curious of the culprit.

Turned out the Cam sensors kept going bad because when my shop rebuilt the engine they did not torque the cam gear bolts properly. Turned out they were 3/4 of the way out and the cam gear was wabbling around in the housing and whacking the cam sensor.