car wont start

[spatulahunter1]

I have a 95 tsi that i can not for the life of me get to start.
The car will crank and sputter and try to start but wont get anywhere. For about the last year anytime i let the car set for more than a week or so i would have this problem where its hard to start. This is the first time where i just couldnt get it to start at all.

I have been reading about this problem and have tried a few things with no success. Today I replaced the Coolant temperature sensor. I also pulled the fuel pump and checked my o ring and sealant ring for the assembly. I tightened down my fuel line connectors to make sure nothing was loose. I pulled my spark plugs and sanded of the carbon deposits on them (car runs a little rich when it starts.) I also visually inspected and checked the connections on all of my plug wires.

This problem started after the vehicle sat for a few weeks while i did the shocks and replaced my 02 sensor housing with an external wastegate vent. I think the problem is from the vehicle sitting and not from any work i did.

What should i check next? I would really like to get this car running soon so I can park my Cherokee and save some money on gas?

 

[EagleTSIawd]

a few tests i would do ( if you havent done so already) is check if you are getting spark. Its a simple test, pull one spark plug out and make it touch ground somewhere where u can see if its sparking as you crank. After that test you can then also look inside the piston and check if its wet from fuel.

 

[cano86]

ENGINE CRANKS BUT WILL NOT START

When the engine cranks normally but won't start, you need to check ignition, fuel and compression. Ignition is easy enough to check with a spark tester or by positioning a plug wire near a good ground. No spark? The most likely causes would be a failed ignition module, distributor pickup or crankshaft position (CKP) sensor.

A tool such as an Ignition System Simulator can speed the diagnosis by quickly telling you if the ignition module and coil are capable of producing a spark with a simulated timing input signal. If the simulated signal generates a spark, the problem is a bad distributor pickup or crankshaft position sensor. No spark would point to a bad module or coil. Measuring ignition coil primary and secondary resistance can rule out that component as the culprit.

Module problems as well as pickup problems are often caused by loose, broken or corroded wiring terminals and connectors. Older GM HEI ignition modules are notorious for this. If you are working on a distributorless ignition system with a Hall effect crankshaft position sensor, check the sensor's reference voltage (VRef) and ground. The sensor must have 5 volts or it will remain permanently off and not generate a crank signal (which should set a fault code). Measure VRef between the sensor power supply wire and ground (use the engine block for a ground, not the sensor ground circuit wire). Don't see 5 volts? Then check the sensor wiring harness for loose or corroded connectors. A poor ground connection will have the same effect on the sensor operation as a bad VRef supply. Measure the voltage drop between the sensor ground wire and the engine block. More than a 0.1 voltage drop indicates a bad ground connection. Check the sensor mounting and wiring harness.

If a Hall effect crank sensor has power and ground, the next thing to check would be its output. With nothing in the sensor window, the sensor should be "on" and read 5 volts (VRef). Measure the sensor D.C. output voltage between the sensor signal output wire and ground (use the engine block again, not the ground wire). When the engine is cranked, the sensor output should drop to zero every time the shutter blade, notch, magnetic button or gear tooth passes through the sensor. No change in voltage would indicate a bad sensor that needs to be replaced.

If the primary side of the ignition system seems to be producing a trigger signal for the coil but the voltage is not reaching the plugs, a visual inspection of the coil tower, distributor cap, rotor and plug wires should be made to identify any defects that might be preventing the spark from reaching its intended destination.

ENGINE CRANKS AND HAS SPARK BUT WILL NOT START

If you see a good hot spark when you crank the engine, but it won't start, check for fuel. The problem might be a bad fuel pump.

On an older engine with a carburetor, pump the throttle linkage and look for fuel squirting into the carburetor throat. No fuel? Possible causes include a bad mechanical fuel pump, stuck needle valve in the carburetor, a plugged fuel line or fuel filter.

On newer vehicles with electronic fuel injection, connect a pressure gauge to the fuel rail to see if there is any pressure in the line. No pressure when the key is on? Check for a failed fuel pump, pump relay, fuse or wiring problem. On Fords, don't forget to check the inertia safety switch which is usually hidden in the trunk or under a rear kick panel. The switch shuts off the fuel pump in an accident. So if the switch has been tripped, resetting it should restore the flow of fuel to the engine. Lack of fuel can also be caused by obstructions in the fuel line or pickup sock inside the tank. And don't forget to check the fuel gauge. It is amazing how many no starts are caused by an empty fuel tank.

There is also the possibility that the fuel in the tank may be heavily contaminated with water or overloaded with alcohol. If the tank was just filled, bad gas might be causing the problem.

On EFI-equipped engines, fuel pressure in the line does not necessarily mean the fuel is being injected into the engine. Listen for clicking or buzzing that would indicate the injectors are working. No noise? Check for voltage and ground at the injectors. A defective ECM may not be driving the injectors, or the EFI power supply relay may have called it quits. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses. Loss of this signal could prevent the system from functioning.

Even if there is fuel and it is being delivered to the engine, a massive vacuum leak could be preventing the engine from starting. A large enough vacuum leak will lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck wide open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking noises while cranking.

ENGINE HAS FUEL AND SPARK BUT WILL NOT START

An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start. The problem is compression . If it is an overhead cam engine with a rubber timing belt, a broken timing belt would be the most likely cause especially if the engine has a lot of miles on it. Most OEMs recommend replacing the OHC timing belt every 60,000 miles for preventative maintenance, but many belts are never changed. Eventually they break, and when they do the engine stops dead in its tracks. And in engines that lack sufficient valve-to-piston clearance as many import engines and some domestic engines do, it also causes extensive damage (bent valves and valvetrain components & sometimes cracked pistons).

Overhead cams can also bind and break if the head warps due to severe overheating, or the cam bearings are starved for lubrication. A cam seizure may occur during a subzero cold start if the oil in the crankcase is too thick and is slow to reach the cam (a good reason for using 5W-20 or 5W-30 for winter driving). High rpm cam failure can occur if the oil level is low or the oil is long overdue for a change.

With high mileage pushrod engines, the timing chain may have broken or slipped. Either type of problem can be diagnosed by doing a compression check and/or removing a valve cover and watching for valve movement when the engine is cranked.

A blown head gasket may prevent an engine from starting if the engine is a four cylinder with two dead cylinders. But most six or eight cylinder engines will sputter to life and run roughly even with a blown gasket. The gasket can, however, allow coolant to leak into the cylinder and hydrolock the engine.

 

[spatulahunter1]

I checked out a few more things today and i am still stumped.

1. I did a compression check that came back good.
2 I checked spark on all 4 plugs by letting it jump to ground. They all sparked.
3. I have fuel in all of my cylinders i can tell when its cranking with the plugs out, (also my walboro is running)

What next? Are there any sensors other than the CTS that I should check? Should i pull the ecu apart and inspect the caps? Any ideas would be greatly appreciated, thanks.

 

[16g-2ndgen]

how is your ignition timing? is your motor in time? there could be a lot of things making your car not start.

 

[spatulahunter1]

the timing belt has been changed within the last 10,000 miles.
This condition seems to be related directly to car being cold or not being started for a few weeks. Last couple times it sat for a while it was extremely hard to start, this time its just worse and wont start at all

 

[spatulahunter1]

I got the car to start today. Unfortunately it didnt smooth out after running for a bit like i thought. It ran really rough for minute and then it backfired loudly and shut off.

Im assuming this means i might have an ignition issue and maybe a cylinder isnt firing correctly so it backfired from the extra gas that wasnt ignited.

After it shut off i read the codes for it off of my auto xray code reader. It said i had one trouble code which was uo6d7, "unknown SAE troublecode description". I dont know if there is any significance to uo6d7 but a google search turned nothing up.

Also when it was running it kept bogging down and i was hearing loud clicking relay type noises from behind the radio where the ecu is, does this mean my problems may be ecu related?

 

[spatulahunter1]

I just pulled my ecu, it looks as though the capacitors are in decent shape. Nothing on the board is leaking so Im guessing its probably fine. Is there anyway to test for sure what shape the ECU is in?

 

[spatulahunter1]

I made a little more progress. The car will smooth out and run for a little while but then i start hearing a clicking relay sound and this makes the car bog down backfire and die. Is there an ignition relay or something that is between the radio and the ecu that could cause me to loose power to the vehicles ignition system?

 

[cano86]

Now that you mentioned it I think there is a relay am not sure what is for but it is right in between the radio and ECU It says something in front of it which start with D

 

[spatulahunter1]

Now that you mentioned it I think there is a relay am not sure what is for but it is right in between the radio and ECU It says something in front of it which start with D

Im gonna pull the radio tommorow and see if there is a short back there that is causing my ignition to fail. That seems like it is the most likely culprit