2000 Plymouth Neon wont start

CHAR411998

MEMBER
2000 PLYMOUTH NEON
4 CYL
FWD
AUTOMATIC
70,000 MILES

Ok,

I am fairly mechanical. I took my kids 2000 Plymouth neon with a2.0 liter 4 cyl apart. I had a valve job done and put everything back together. All went well and I started it. It started right up and warmed up normally. As it was idling and about 15 minuted into the first start up I started accelerating it slightly. It died and will not start. It sounds as if it is backfiring thru the throttle body. It sounds to me like an older model GM product when it is 180 degress out of time but it ran so well for the first few minutes. Any ideas where to start. I have checked everything a second time and all is correct. I even removed the front motor mount and checked the placement of the crank and cam to make sure it was correct. I made certain I was on the compression stroke at TDC and then checked the timing marks on the cam sprocket. Im totally lost as to why this happened unless I am out of time some how. Thanks, Scott

9 Replies

BMRFIXIT

MECHANIC
19,053 POSTS

This is the time when you walk away
take a brake and than come back and start fresh do you have spark do you have fuel and fuel pressure check injector pulse Do a compression test recheck timing marks
cycle key on off on off on get the codes if any with key on do you have check engine light on? Does it do off as cranking? Let me know what is missing if any if you have scanner check if in SYNC crank and cam

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Friday, March 27th, 2009 AT 6:32 AM

CARADIODOC

MECHANIC
33,916 POSTS

The last thing BMRFIXIT mentioned was "check if in SYNC crank and cam".

If the timing marks are right on, but there's a code for cam and crank out-of-sync, check for a broken dowel pin between the camshaft and sprocket. Pin breaks, cam slips a little on the sprocket, "Check Engine" light comes on.

The cam sensor is on the other end of the camshaft, so when the cam is late, so are the sensor pulses, but the timing marks on the sprocket are correct. When the cam is the equivalent of one tooth off, the Check Engine light comes on. Two teeth off, and the engine computer shuts the engine down by turning off the Automatic Shutdown )ASD) relay. Three teeth off, and a piston can hit a valve.

The ASD relay is turned on by the engine computer for about two seconds when the ignition switch is first turned on. It doesn't turn on again until the engine computer sees engine rotation, (cranking or running). But in the case of cam and crank signals that don't agree, the computer also does not turn the relay on.

The ASD relay sends voltage to the ignition coil(s), injector(s), and fuel pump or relay, so all of these will be dead. Be aware, I did have one that had intermittent spark on two plug wires, and the ASD relay was clicking on and off during cranking.

Holler back with what you find.

Caradiodoc

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Saturday, March 28th, 2009 AT 10:17 PM

CHAR411998

MEMBER
7 POSTS

Ok,

I walked away for a day or so.

I have spark on all four plug wires that is bright blue and sparks like normal.

I do not have a fuel pressure gauge but I do have fuel. I can hear the fuel pump turning on whent he key is turned on. I checked for fuel at the fuel injector bar (rod) and there is pressure there along with fuel flow.

I completed a compression test and all is within normal limits.

I rechecked the timing marks for a third time and all is good.

I cycled the key on off on off on and the engine light DID NOT come on.

When the key is in the on position the light comes on but goes off a short time later.

As the engine is cranking the engine light goes off also.

I do not have a scanner to check the SYNC of the crank and the cam.

I bought a noid light set today and checked each fuel injector harness. I got excellent spark to injector 1 and 3 but nothing to 2 and 4 (using piston 1 as injector number 1 as a guide).

Let me know what you think from here via this wonderful way of communicating.

Thanks so much,
Scott

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Monday, March 30th, 2009 AT 9:18 PM

CARADIODOC

MECHANIC
33,916 POSTS

Dowel pin between the camshaft and sprocket.

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Tuesday, March 31st, 2009 AT 2:59 AM

BMRFIXIT

MECHANIC
19,053 POSTS

We are going to assume that the fuel pressure and fuel flow OK
no injector pulse at two cylinders?
Use a test light turn key on check for battery volts at the DR DRN/ORN wire
all cylinder should have power
if no check for a short in the wiring harness
if you have power at all
let me know next step would be to check injector drive from the PCM to the injectors