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Discussion Starter · #1 ·
Hello, I'm new here. I recently bought a 99 beetle 2.0 gas. Cel was on when I bought it, but it was running great. 2 days later it wasn't. Multiple misfires on 2, 3, and 4. Also the fuel trim is too lean. I bought a bunch of parts and had my dad put them on and it seems worse. The parts changed: plugs, wires, coil pack, fuel pressure regulator, 4 fuel injectors, mass airflow sensor, and the upstream oxygen sensor. This is my first car and after putting all of these parts on, my dad is at a loss. He even tried spraying carb cleaner on all vacuum lines and connections looking for a vacuum leak. Any help will be greatly appreciated as now I am broke and still driving my dads truck.
 

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Notorious DOM
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Let's start with air. did you change the air filter?

Next, fuel. Did you change the fuel filter?

OK. there is not a spark filter...

Air, Fuel Spark.

Basics.

Go next...
 

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Discussion Starter · #3 ·
The air filter and fuel filter have also been changed...forgot about it lol on of the first things we did
 

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Discussion Starter · #5 ·
Thanks...I'll scan the car when I get off work. I was gonna buy a fuel pump but after everything I've already put on the car and its still not running right I wanted to get on here and see if we was headed in the right direction
 

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Need to see Freeze Frame data. This will give the best snap shot as to what is going on.

If you have a decent scan tool that supports Live/Realtime Data, see what the MAF reading is in grams/second at idle as well.
 

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Discussion Starter · #7 ·
OK so the codes are: PO300,PO302,PO303,PO304. No other codes have shown up because my dad doesn't want to run it.
 

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Discussion Starter · #9 ·
Need to see Freeze Frame data. This will give the best snap shot as to what is going on.

If you have a decent scan tool that supports Live/Realtime Data, see what the MAF reading is in grams/second at idle as well.
Freeze frame data: trouble code po300, rpm1098, load? 5.1, coolant temp 97F, st ftrm1 0.0, Lt ftrm 0, vehicle speed 0, fuel system 1 open.
 

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Discussion Starter · #10 ·
Need to see Freeze Frame data. This will give the best snap shot as to what is going on.

If you have a decent scan tool that supports Live/Realtime Data, see what the MAF reading is in grams/second at idle as well.
Maf(LB/M) @ idle is .86
 

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Discussion Starter · #11 ·
My dad says that he can't hardly keep the engine running when its cold, buy when the temp gets up above 100, it seems to run fine except the fuel trim being at 25%
 

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Fuel Trim at +25% means either massive vacuum leak and/or a MAF that is under reporting. Most Fuel Trims max out at +/- 25%. Be careful as a big vacuum leak WILL typically cause the MAF to under report because air is bypassing the MAF. Smoke testing is the EASIEST way to find vacuum leaks. Search YouTube for Smoke Test ideas, Scotty Kilmer is one guy, but there are many simple ways you can smoke test and intake for air leaks.

Would prefer to see the MAF reading in g/s rather than lbs/min, I will try to converter, but usually you can change the readings from English to Metric in the OBDII tool set up.

0.86 lb/min converts to 6.5 g/s which is too high for the 1.8l but you may have the engine running faster than 700 RPM to keep it running.

I would be looking for vacuum leaks first as these are VERY common on 10+ year old cars.

Tell dad to SLOW down, injectors probably were fine, they rarely have problems. I would suggest putting the original MAF back on the engine for a test as well as there are many Asian counterfeit MAF's on the market that do not work properly.
 

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Carb cleaner rarely will find sneaky vacuum leaks, most are on the underside of hoses or lower in the engine compartment. This is a common way to find leaks, however, smoke testing is far more fool proof and will find any and all leaks, even crankcase air leaks.

Power brake boosters can leak and they are tricky to smoke test because of the input check valve to the booster will not let smoke in and you have to look closely under the dash for the smoke leaking out of the booster if it is bad. You can usually hear a leaking booster from in the cabin if you know what to listen for.
 

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As jfoj stated, a plus 25% fuel trim suggests a very large vacuum leak, I would carefully check all hoses, hose connections, intake manifold integrity, PCV etc.

Also, seeing as you recently purchased this car, you may want to make sure that the MAF assembly is correct for the vehicle, make sure that the housing is the correct diameter in case the previous owner had ideas.

I have read about people attempting to increase power by installing a 3" housing, without the appropriate injector size increase/software/hardware, this will definitely put your fuel trim off the scale on the lean side.

 

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Discussion Starter · #16 ·
Found 1 vacuum leak on your car. Fixed it, but still missing when cold. Once it warms up, runs fine. Fuel trim is still high. Codes set are p1128, p0300, p0301,p0302,p0303, and p0304.
 

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Injectors and O2 sensors do not have much to do with Lean conditions.

MAF, hard to say if this is a contributor. The BIGGEST mistake people make is buy the $50-$75 replacement MAF from the parts store or ebay. There are SO many Asian counterfeit MAF's on the market that cause people so many problems. This is because the mindset is I just replaced the MAF, the problem cannot be due to the MAF!!

Cold start problems are often due to vacuum leaks. As I mentioned, you will never find them with spray as most are hidden and in places you do not spray. Might even be crankcase air leaks as well.

Search YouTube for Scotty Smoke Test and see what Uncle Scott and his friends do.
 

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Discussion Starter · #20 ·
We did the smoke test yesterday and found one leak as my previous post states. Fixed the leak but the car is still running lean and misfiring. Once the car warms up it stops misfiring but its still running lean
 
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