1997 Ford Ranger Cranks/No-Start

 The engine cranks (starter engages and spins the engine) just fine so starter related system is fine. Fuel pressure is easy to test. Like the Sun slogan, we test - not guess. You don't have to use an expensive pressure tester but you do need an accurate one. Ideally with key on and engine cranking you want to see between 35 and 45 psi. of primary fuel pressure.

Primary fuel delivery is good. What about secondary? I just want to see if I'm getting injector pulse so a noid light is fine. During crank the noid light should flash at each pulse. I get no flashing noid light so I am seeing nothing to open fuel injectors. Instead of a video of a noid light not flashing I'll just use a picture of a noid light not flashing. VBG. 

Now I will assume I have power to the injector because it comes from the EEC Power Relay which also powers the Fuel Pump Relay and since my fuel pump is working I want to check I have spark at the plugs during crank. If I have spark but no injector pulse then I'm looking at fuel controls for problems but if I have no injector pulse and no spark then I'm looking at triggers, such as a crankshaft position sensor. 

I have no spark present at the spark plug wire during cranking.

If the computer isn't seeing an engine cranking condition it won't pulse injectors or fire ignition coils. It is a good time to use a scan tool to see that the computer is working and if it notices a fault. The computer is functional and it does have a memory code P0320 which indicates a problem determining engine rpm, which could also point at a bad crankshaft position signal.

If I watch the data pid for engine rpm while cranking I don't see activity. 

  The ECM connector is fairly east to access and I can check my crank sensor signal at the ECM. 

You can remove the connector cover for access to the wiring and backprobe or you can use a breakout box. 

I know which method I'll be using since I don't have a Ford OBDII breakout box.  I don't see a crank signal to the ECM during cranking so I'm going to access the crank position sensor. 

Not an easy area to access. The wiring near the connector was bad so I replace the sensor and repaired the wiring. 

Once finished, we have a crank signal and a start. On the road again. 

Kenny@ggauto.repair

CAN Problem (Undercar Digest April 2015 Scan)

 

Converter Ballooning (Gears article)

 Converter Pressure Gears article

Mazda6 NOT-P switch fault (Gears article)

 Gears NOT-P article

1998 Dodge Ram 1500 Cranks, No-Start

 This one does engage the starter and the engine spins as it should but the truck doesn't start. The technical term for that is a crank/no start condition. The engine cranking properly means we don't have to consider any starter or battery related issues and can consider those as tested and passed. This is when some might say I think its the fuel pump, or similar guess. When you are the one supposed to find and repair you can't just guess and try that. I don't do checks in a particular order, I work with the truck. It isn't the fuel pump. The fuel pressure is easy to test on this, and within specs. 

We can move on. Just because I have primary fuel pressure in the rail does not show that I have secondary fuel delivery via the fuel injectors which are electrically operated. The quick test for that would be a noid light to let me know if the injectors are getting power and ground signal during cranking. The light simply plugs into the injector connector and will flash as the injector pulse is present if that system is working. 

We have cranking, primary and secondary fuel delivery. We are going to look for secondary ignition (spark) from the coil next. The coil is very easy to access on this truck and we want to look at the connection and ignition coil tower for obvious problems before beginning the spark output test. I see the problem. Rodent damage to the ignition coil wiring harness. 

I repaired the wire damage and we are road ready! Diagnostics are about understanding how the system works and forming a logical testing sequence to gather the information you need as quickly as is possible. There are systems that are very difficult to diagnose due to the complexity of the system as designed and occasionally due to the atypical cause of the problem but the same method will apply, understand the system, test logically. You are actually more looking to put aside what will not be the problem so you can more quickly find what is the problem. I call it the Cat in the Hat method. To paraphrase, the way to find the problem is to find what isn't the problem. 

Cat in the Hat Method

See ya next time! 

Kenny@ggauto.repair

1998 Ford Mustang 3.8 Cooling Fan Operation

 After replacing a failed lower radiator hose and filling the cooling system I wanted to make sure the electric radiator cooling fan was working properly. 

My Alldata service information says the fan should come on at 221F then stop running when it lowers to 200F. I usually run the engine at about 1500 rpm with the car sitting still while watching the conditions are being met. I want to mention that my Ford service information is less precise about the temperature but says the fan should come on when the temperature gauge passes halfway and turn off when it returns to halfway. The half way point being normal for the conditions. I'm bringing that up because that is exactly what the car did. The engine coolant temperature at just past half way was 210F and that is when the fan came on, at returning to half way the fan turned off at 204F. 

A scan tool graphing the data shows the engine was at 176F when the recording began and peaked at 210F. 

. You can see the graph lowering from the 210F to the 204F before it turns off the fan and begins the cycle again. 

The system looks to be working properly. 

Kenny@ggauto.repair

2014 Pathfinder Intermittent No Acceleration

 The complaint was that sometimes after braking and then attempting to accelerate, it would not accelerate. I drove this around all morning and it did do that once and no more. After looking at scan data and memory codes recorded later and never again seeing the problem I parked it outside and was about to call the customer to update her. I happened to look outside at the car and the brake lights were on. I traced the brake light problem to the brake light relay being stuck on. I took the relay apart and the first 3 times I pressed it closed with my fingers, it stuck in closed position. After that, worked fine again. I replaced the relay and case closed because the car is drive by wire and because the relay was sometimes sticking on the ecm was trying to prevent engine run away and not allowing proper acceleration, due to thinking brake was on. 

I have since learned that Nissan has a TSB concerning the problem and is deleting the relay all together, 

Nissan TSB

Kenny@ggauto.repair