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I have had a hard to start problem when the car is warm for quite some time. The car can sit for a month and start right up but after warm it has to crank quite some time to start. My first thought was loosing fuel pressure but surly sitting for a month pressure is gone.
Any suggestions? Just getting tired of it.
i am certainly not an expert on the m20 but i would think that itd be the temp sensor that controls the ECU and tells the fuel system when to run rich. it might be bad causing the motor to think that it always starting cold and then enrich the mixture? just a thought
The first things I’d consider would be intake leaks, a bad ECT sensor, or leaking injectors.
Thanks for the response. This same problem has existed both before and after a rebuild. I am pretty sure there are no intake leaks but will check with some ether. The injectors have been cleaned and tested when I built the car in '07 but I’m sure they could be leaky one. How do you test for this. Also, all the sensors were replaced in '07. I will test some of the spares I have and change the one out in the car and see if that helps.
Please keep the ideas coming.
The only sure way to locate intake leaks is via a smoke test. Carb cleaner or the like only works on leaks close to the head.The complete list of possible causes of an intake leak is:
Intake boot
Throttle body gasket
ICV hoses & connections
Brake booster, hoses, and connections
Crank case breather hose
Evaporative control hoses, valve, and expansion tank
Fuel pressure regulator & hose
Injector seals
Valve cover gaskets & bungs
Oil filler cap
Dip stick o-rings
Oil return tube o-rings
The only way to check injectors is to have them flow tested. All you can do yourself is to pull the injector rail, jumper the fuel pump relay, and see if any of the injectors drip.
Well I can get a smoke bomb and set if off in the intake. I guess that won’t hurt anything will it?
haha, sorry i had to laugh as the smoke bomb idea made me remember the story of the guy who ran sand in his intake to try and hone his intake haha, but no i dont see why it would hurt anything unless it blew up inside and left pieces everywhere, then youd have some fun trying to clean it out.
I was actually talking about the type of smoke bombs we use here at work sometimes. No explosion. Used to find leaks in sewer lines. I am just afraid they may produce way too much smoke. You just light the think and it produces a lot of smoke volume. Maybe they have small ones.
Find a local mechanic that has the machine. Its easy and quick and they should not charge too much. I found a few on my car when testing it and even the throttle body butterfly pin had a minor leak. Or find the link Ranger put on here someplace to make your own. Just need some compressed air w/ regulator, a can, a some hardware and you can make your own.
That should not hurt anything, but then it probably won’t help you find the leak. A smoke test machine will pressurize the intake with smoke filled air, which will wind up seeping out of the leaks. The pressure is just as important as the smoke.
Did the injector leak test and it seems that maybe half or more are leaking. So where can I get NEW replacements?
The odds are good that all your injectors need is cleaning and flow testing. But if you want to hedge your bet, go to a salvage yard and get a set of used injectors. Send all 12 to RC Engingeering and have them pick the best six for rebuilding & cleaning. That will be cheaper than a set of new injectors.
How do you perform this test? Were the injectors previously cleaned?[/quote]
I removed the injector fuel rail with injectors still in it and fuel lines still connected. Jump the fuel pump relay. Then turn on your kill switch. The fuel pump will run and pressurize the system. Look for any fuel seeping from the injectors. Seemed easiest for me to point the injectors up and the ones that had fuel running down the side were leaking.
Now in doing his I have run into some other issues.
Two of he injectors left their caps in the intake and when trying to retrieve them one fell into the head. I had to remove the intake to get it out.
In reinstalling the intake, a wire to the starter solenoid got broke. The small wire that looks like to ground from the wire harness.
In removing the nut on the stud of the solenoid the stud came out.
Can’t get the stud back in so think I have to remove/replace starter.
The odds are good that all your injectors need is cleaning and flow testing. But if you want to hedge your bet, go to a salvage yard and get a set of used injectors. Send all 12 to RC Engingeering and have them pick the best six for rebuilding & cleaning. That will be cheaper than a set of new injectors.[/quote]
I have two spare injectors that were cleaned in '07 along with the 6 in the car that went in the initial build. RC did the cleaning back then. I installed the two of them. I also have a boat load of spare used injectors so looked through the pile and found a good looking one and installed it. They do not appear to be leaking.
I next rigged up some jumpers and jumped power from the car through my momentary switch I use in the diagnostic plug for running the starter. Hooked this to the injector and I was able to fire them off into a coffee can. The new previously cleaned injectors definitely had the best pattern. The others were not too bad including the used one I installed. I found some info on how to DIY clean them and may try that after the next race.
I read where the places can clean them but not tell if they are leaking. This car has had this problem since the original build in '07 so something was wrong then.
Also, the reason I chose this test first instead of the smoke test was that when I was removing the AFM/Air filter assembly to measure the size of the intake boot so I could make a plug, I noticed strong gas smell. Car had been sitting for a few weeks.
I know that RC Engineering does test for leaking injectors, spray pattern, and flow. If you have enough spare injectors, send a set off and have them rebuilt.
I have an intermittent hard start problem. Sometimes it will fire right up and other times (doesnt matter if its warm or cold) it will just turn over a bunch then barely start to fire then roughly start up and idle. At WOT it runs fine with no shuddering but at idle it seems like a plug is fowling or its loading up (sounds like it has a big cam in it) Any ideas on where to start looking at this problem? could it be an injector problem? these injectors are from valley motor works and have been flow matched and cleaned. Other than the hard start sometimes the car runs flawlessly.