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Hard Start when Warm!
*Just as a disclaimer, I'm fairly new to the world of mechanics*
But, it seems that being poor encourages you to learn things on your own. 1999 182,000 miles Car runs beautifully after it has started - But hard start when warm. Hey all, I've been smacking myself silly trying to figure out what is happening with our Maxima. So, back in April of this year, our FPR slowly began to go bad. Eventually the inner diaphragm cracked and so the entire fuel pressure on the rail fell apart causing tons of backfire and random misfire. At first I had no idea what it could've been, so I decided to start off with changing the park plugs. I picked up some Iridium NKG's and changes all six. However, when I got to the last ignition coil, I noticed that the coil was snapped in half and was held together by some sort of glue. So, I decided to change that too. After all this, no improvements. I figured perhaps the other ignition coils are bad, so I tested them as per the Haynes Manual, but all they all seemed to be healthy. So after this I decided to inspect the fuel injectors. After relieving pressure within the fuel lines, I took apart the Upper Manifold and carefully took out each injector. 3 of the six were destroyed. The smaller O-rings were missing and the end caps were cracked. And so I ended up replacing all 6 injectors and the fuel filter (just because) put everything back together, still nothing! Finally, after some more research I decided to replace the FPR. I started the car, and vroom! Started right up and ran like a champ! $350 later and all has been well for quite some time! BUT! I now have codes for Knock Sensor P0325 and Ignition Primary 1320, that just keep coming back after resetting them! ...until last month. Here is where the hard start comes in. Over the course of the month of August, I noticed that my starts were not as crisp as they have been. I noticed that sometimes I had to crank just a taaaad but more than I was used to. Fast forward a month later, and it has become very very difficult to start the car after it has warmed up. On cold starts, everything is perfect, start right up. On warm starts, it cranks, cranks, cranks, and sometimes clunks. Finally after 3 or 4 tries, the engine will finally turn on. It got to the point where I killed my old starter; the entire mechanism inside was destroyed from all the cranking. Finally I replaced it with a new Reman from Duralast Gold a couple weeks ago, but the same problem is still happening I noticed that after the car is warm, I would have to either apply a bunch of throttle or take out the fuse for the fuel pump; only then will start right up! This led me to believe that I have a rich fuel condition at start up. No other engine codes have come forth either. So after some more research I found out that sometimes, a messed up Coolant Temp Sensor would only send a cold signal to the computer, even after the engine has reached operating temperature, which would mean that the mixture would constantly stay rich. So I replaced this too...and while my start ups have somewhat improved...I am still having trouble restarting after engine has warmed. I have no idea what to do. My mechanic says it's the knock sensor 100%, but I'm getting mixed answer from people saying that KS won't cause a hard start. I'm stuck and don't know who to proceed Summary of Symptoms Hard start after engine has warmed Slightly decreased fuel economy A very small decrease of power during highway acceleration Engine Codes: P0325 P1320 Components Recently Replaced Spark Plugs All 6 Ignition Coils All 6 Injectors FPR Fuel Filter Air Intake Temp Sensor Ignition Switch Engine Coolant Temp Sensor Coolant Temp Sending Unit Starter (Cleaned Crankshaft Sensor) (Cleaned Idle Control Valve) (Cleaned Throttle Body) Note: Extra throttle or taking out fuel pump fuse facilitates an easier startup Battery voltage after operation is around 13.8 otherwise it is at 12.5 Last edited by NissanTech; 09-23-2015 at 02:16 PM. Reason: Removed useless links |
#2
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Lets start with the P0325 code for the knock sensor. It's very unlikely that the knock will cause a hard to start situation. The P1320 code is set when one (or more) of the ignition coils resistance is out of specs. You probably used after market ignition coils, and that's usually the cause of P1320 code.
Unfortunately there are still many things that could cause a hard start: - Excessive carbon built up in the combustion chamber. - Faulty IACV / AAC valve ( The valve opens when engine cold and reduce the opening when the engine is warm up ) - Sticking PCV Valve - Sticking EGR Valve Common problems are the excessive carbon built up in the engine and the faulty AAC valve.
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#3
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Quote:
I remember when I removed the Upper Manifold in order to replace the back 3 fuel injectors, I cleaned the upper part of the EGR valve which was then totally clogged with carbon soot, but I never thought of removing it all the way and cleaning it thoroughly. I will check the IACV as well as the PCV and the EGR. Could carbon buildup or a failed PCV really cause this much of a mess when the car is warm? Thanks again! |
#4
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first you have to resolve code P1320. an or some ignition coil/s is/are bad. read the thread 2000 Nissan Maxima P1320 Code, post #17. the knock sensor code may go away once P1320 is gone.
does the starter hesitate while starting? if so, you may need to install additional ground wire from the battery negative to the transmission housing (or near the starter). (make good electrical connection between battery negative & starter housing.) suggest you go to autozone (or other auto parts store) for free battery & alternator test. Last edited by OilCanObserver; 09-29-2015 at 04:14 PM. |
#5
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Quote:
Still getting a hard start though. (I will try to post a video of the symptom and the temporary fix that I impose on it) My father thinks it may be the Ignition Coils wreaking all this havoc, but I don't think so, I think its more serious than that. We shall find out soon enough! I shall fill you guys in as soon as they come in and I replace them. I will also look into the grounding, that could also be a very probably cause! |
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hard, start, warm |
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