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Juan Crespo
Juan Crespo, Tech Trainer
Category: Car
Satisfied Customers: 1513
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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2005 suzuki verona with p300, p0301, p0302, p0303, p2096, It

Customer Question

2005 suzuki verona with p300, p0301, p0302, p0303, p2096, It doen't want to go. I change new spark
Submitted: 1 year ago.
Category: Car
Expert:  Juan Crespo replied 1 year ago.

Hi there. Thanks for using our service!

Based on those codes and the lack of power you mention, the problem is probably fuel-related. To confirm, measure fuel pressure. It should be about 45 psi. If less, replace fuel pump and filter.

You might also have to replace the fuel pressure regulator if, in addition to the lack of power, the engine cranks longer than normal before starting.

Best Regards.

Customer: replied 1 year ago.
Check fuel pressure is ok, change new fuel filter, same problems.
Engine start ok, idle is ok, only problem is not speed more than 30 mph,
Check engine light flashing, code p300, p301, p302, p303, and p2096
Customer: replied 1 year ago.
Problem is not solved, please let me know what else can be?
Expert:  Juan Crespo replied 1 year ago.

It is very important to check fuel pressure with a pressure tester to confirm it is around 45 psi. If that is so, then we need to check engine vacuum to rule out the possibility of a partially clogged exhaust system. Here is what a vacuum test tells us:

Normal Engine Operation

At idling speed, an engine at sea level should show a steady vacuum reading between 14 in. and 22 in. Hg. A quick opening and closing of the throttle should cause the vacuum to drop below 5 in., then rebound to 23 in. or more.

General Ignition Trouble or Sticking Valves

With the engine at idle, the continued fluctuation of 1 to 2 inches may indicate an ignition problem. You should check things like spark-plug gap, primary ignition circuit, high-tension cables, distributor cap or ignition coil. Fluctuations of 3 to 4 inches may point to sticking valves.

Intake System Leakage, Valve Timing or Low Compression

A vacuum reading at idle that is much lower than normal might indicate leakage through the intake manifold gaskets, manifold to carburetor gaskets, vacuum brake booster or the vacuum modulator. Low readings could also be caused by very late valve timing or worn piston rings.

Exhaust Back Pressure

Starting with the engine at idle, slowly increase engine speed to 3,000 rpm. Engine vacuum should be equal to or higher than vacuum at curb idle. If vacuum decreases at higher rpm, an excessive amount of back pressure is probably present due to a restriction in the exhaust system.

Cylinder Head Gasket Leakage

With the engine at idle, the vacuum gauge pointer will drop sharply every time the leak occurs. The drop will be from the steady reading shown by the pointer to a reading of 10 in. to 12 in. Hg. or less. If the leak is between two cylinders, the drop will be much greater. You can determine the location of the leak by doing a compression test.

Remember, engine problems can affect transmission performance. If you suspect an engine problem, connect a vacuum gauge to the intake manifold. Note the location and action of the vacuum gauge needle, and use that information to determine the engine problem. Correct the engine problem before doing extensive calibration work on the transmission.

Please perform the vacuum tests described above; then share the various readings with me along with the actual fuel pressure in psi so I can get a better idea of what is exactly happening with your engine.

Best Regards.

Customer: replied 1 year ago.
this is straight 6 engine, but it only misfire first 3 cylinder, I checked fuel pressure is 44psi, check engine pressure 130psi for each cylinder, check vaccuum OK, no vacuum leak. I try to delete code, and test drive, it go ok for the first 3 minutes, after that it lost power
I don't know what going on, try everything you said, still the same
Expert:  Juan Crespo replied 1 year ago.

OK. The best way to diagnose this issue would be with a scan tool capable of reading engine data. That way we could see what's happening to the power feed for coils 1, 2 and 3.

Without the scan tool, we could inspect harness connector C118 (see attached graphic) to see if there is where the power loss is occurring. Other than that, it would be a matter of checking each individual coil and injector circuit on those three cylinders to determine where the problem is (see attached diagram).

Please let me know what you find.

Best Regards.

Customer: replied 1 year ago.
Can you Give me A diagram showing where To hook up to test exhaust back pressure
Expert:  Juan Crespo replied 1 year ago.

The easiest point where you could install a vacuum gauge is on the big vacuum hose going to the brake booster; just use an adapter. As an alternative, you could use a "tee" fitting on the vacuum hose going to the fuel pressure regulator. Basically, anywhere where there is manifold vacuum at idle is good.

Best Regards.

Customer: replied 1 year ago.
My car is still same problem, I did everything you tell me, I check everything is ok, but my car was not speed over 20 mph.
Expert:  Juan Crespo replied 1 year ago.

I'm sorry, but I'm a little confused by your reply. Please keep in mind that while I can provide you with technical guidance, working on this type of issue will require you to have not only access to several different automotive tools, but the skills to use them as well. As I’m unable to hear, see or touch your vehicle, it is very important that you provide as much information as possible.

What exactly do you mean when you state "I did everything you tell me, I check everything is ok"? Did you confirm all three injectors and coils were firing?

Customer: replied 1 year ago.
I swap coil 1,2,3 to 4,5,6 and injector 1,2,3 to 4,5,6 still got code p0300, p0301, p0302, p303
And p2096. Changed new fuel filter, check fuel pressure is 44 psi. Car started ok (turn on right away) , idle is ok. Engine light wasn't on when car in idle, when drove car 3 minutes check engine light start flashing and it lost power
Expert:  Juan Crespo replied 1 year ago.

I'm sorry if you misunderstood my instructions, I did not tell you to swap coils or injectors. What I did tell you to do was

"The best way to diagnose this issue would be with a scan tool capable of reading engine data. That way we could see what's happening to the power feed for coils 1, 2 and 3.

Without the scan tool, we could inspect harness connector C118 (see attached graphic) to see if there is where the power loss is occurring. Other than that, it would be a matter of checking each individual coil and injector circuit on those three cylinders to determine where the problem is (see attached diagram)."

Did you check vacuum as I previoulsy indicated? If so, what were the results? How about checking connector C118? Did you check the individual circuits and connectors for cylinders 1, 2 and 3?

As a technical expert all I can do is recommend the procedures you need to perform to diagnose the issue with your vehicle. It is ultimately up to you to have the necessary skills and tools to execute those procedures.

Best Regards.

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