Rough Starts for E420; Injectors Cleaned, etc., - now what???
 

When first starting the car in the morning, it feels like somebody is doing jumping-jacks on the front of car. This lasts for around 30 to 60 seconds.

When starting the car after it has been sitting for awhile it is not a smooth start (not nearly as bad as the firsm morning start, but still not good). It kicks over, feels like a big miss and then kicks over again.

The injectors were removed, cleaned and had the following items replaced - pintle caps, filter baskets, o-ring seal top & bottom. Before having the injectors removed, the jumping-jack problem was once every couple of weeks and there was no problem with restarts.

Also, the wiring harness has been replaced. Additives have been tried (Techron, Heat (for removing water) & octane booster). No difference.

Needless to say, the car is headed back to the shop. Assuming the injectors check out okay - what else could the problem be???

Thanks,
John

I wonder if this problem is related to your engine missing at idle and steering wheel vibration?

I'm guessing there's a possible vacuum leak causing the idling vibration & the fuel pressure regulator or accumulator for the morning starts. But these are just guesses. With fuel injectors going through a minor rebuild; I doubt it is a leaky fuel injector.

After reading 100s of posts, I did notice one of your posts said if the air mass sensor failed (or is failing???) then the idle could oscillate. The idle is oscillating but not enough to notice on the tach, but you can hear it alittle. While giving the car alittle gas (foot on brake and car in gear), the oscillation is easier to hear. While doing thing, I'm giving the car just enough gas to to raise the oscillation noise/vibration - but the tach is still pretty much at the same 500 RPMs. Can air mass filter gradually decay in performance, or is dichotomous - when they fail it is all at once?

One thing i did notice, the RPMs don't change whether the car has the AC on or off. Is this normal (I expected the RPMs to be alittle higher with the AC on).

While in drive, if you give the car just alittle more gas (the RPMs barely go up - if at all) then the vibration goes away. What influence the '95 420's idle speed? While driving, the car feels normal. So, it sounds logical to me that it something control the idle speed, or something providing an input to the idle speed.

I'm going crazy with this (alittle broke too!).

Thanks, John.

I listened to the car for awhile and noticed a whining sound coming from the rear of car. It was very faint and sounded like a real slow squeak (not high in pitch) - kind of like somebody cleaning a glass window.

I thought it might be pressure escaping from the gas cap, so I opened it and released the pressure. Got back into the car and could still hear it. You can't hear it from the outside of the car; there's too much engine and exhaust noise.

Whether the car was in park or drive, you can still hear and the frequency didn't seem to change. I tried revving the engine in park, but cabin noise increases and you can't hear the squeak any more - I want to see how it changed with acceleration.

Anyway, I'm guessing this is the fuel pump crying, "Replace me!"...

Sounds exactly like the fuel pump.

You actually have two of them.

I'm wondering if this is the source of all your problems...

You need to check the fuel system pressure before replacing anything. From what you've described it sounds like the system isn't holding pressure when not running. This would cause long cranking and/or rough running following start-up because the pump(s) need to build up lost pressure before the engine can start and run smoothly. I honestly haven't seen too many happy endings after using fuel additives. A worn injector that's leaking down over night or a fuel pump check valve that's leaking internally needs to be replaced. Simply connect a fuel pressure guage and verify the correct pressure(s) with the engine running. If everything is OK shut it off and monitor the pressure(overnight if necessary) to see if it drops below spec. From your description I think you'll see a pressure loss within an hour or two if, indeed it's fuel-related. Also, don't overlook the ignition suppressors. They're easy to test and cheap to replace. If it's an LH-SFI 119 engine have a look at the caps and rotors too. I've tossed hundreds of them in the trash over the years. A little bit of green stuff inside the cap is all it takes to cause a running problem. Good luck

I had lots of problems with sluggish morning starts. Same symptoms that you describe.

I had my valve seals changed and the problem went away.

ILUVMILS-

The car is going back in tomorrow night so they can do a fuel pressure check overnight. We're going alittle crazy with this problem trying to figure out if the idle and starting problems are part of the same issue or two seperate issues. Since neither is getting resolved, it feels like we're going in circles.

AuctorEcclesiae-

The car isn't sluggish at all; just the king of mis-fires in the morning. After 30 seconds or so, it settles down. While it misfiring, the car will rev just fine - just with a whole lot of shaking.

suginami-

Oh great - two parts they can replace :eek: While not excited to spend $200 per pump, I would like to see the car just completely fail one of the tests. However, I'm still not optimistic. How do the fuel sending unit, fuel pressure regulator and/or accumulator figure into the "rough start" problem?

John, I felt the same way you do now when my car was experiencing several different driveability problems. The diagnosis was apparently difficult for the technician to make, and was replacing a lot of parts that didn't seem to fix the problem completely. The car was getting better in small increments, but not completely. When the technician was testing parts, I was just hoping that something would be diagnosed as bad, just so that I would have a resolution.

I threw a ton of parts at the car to fix it. More than what you have so far.

If you'd like to read my saga and have time to kill, get a hanky first to wipe the tears from your eyes.

Do a search on all the posts I've made, and go to the very first posts I've made.

I've spent a fortune on this car. More than I'd ever imagine. But at least I won the battle, and the car really does run beautifully.

suginami -- I've read most of your posts and have been taking alot of notes! In the last 18 months, the car has set me back over $8k in maintenance and repairs. Add onto that another $3.5k for a repaint, $3k for a stereo and about another $1.5k in fun stuff. Hmmm - $22k for the car plus another $16k -- A monthly run rate of $1,700! What's the word I'm searching for --- "oooops"? I'm in so deep in this car, I would rather tell my fiancee that I cheated on her than admit how much this car has cost!

But yes, the dream (that tiny, tiny speck of light at the end of tunnel) is that the car will be back to where it should be and then it will go another 30k to 50k miles without issue. At 95k is has plenty of life left in it. On flip side, I took a tour through Parts Lane and totalled up all the major components between the fuel pumps to the engine and then a couple other sensors. This could easily go another $2k to $3k. The hard part is figuring out when just to give up.

The amount of money I've spent is about what you've spent in the 16 months I have owned my car.

I haven't broken apart the really necessary maintenance and repair expenses from the "unnecessary" expenses (new wheels, shift knob, steering wheel, euro headlights, window tint, high-end audio equipment, bumper respray, etc.).

The two categories of expenses total almost $12,500!!!

I only paid $9,500 for the car, so it was a steal.

But, I have to tell you, at the end of the day, the car is so clean and immaculate it takes your breath away. It not only looks like a brand new car, it runs flawlessly.

And I love it. I can't imagine driving anything else.

The car was dropped at the shop earlier this evening. From a cold start yesterday, the idle reach an all-time worse - AFTER the injectors were rebuilt & wiring harness replaced. :mad:

As for the fuel pump noise mentioned earlier, it hasn't happened again. Oh well... The short term plan is a fuel pressure test; I'm guessing the fuel pressure accumulator or something along those lines is amiss. Also, looking at the 90k service invoice, they didn't change the fuel filter. So that's on the list of things to be replaced.

On the plus side, got a new Cooper S as the loaner. Nifty car with navigation system - but the overheat light came on/off after a turn - I'm guessing the fluid level is low. Pretty tight car, but the acceleration isn't what I expected - zero torque. Reminds me of the Honda S2000 - keeping the rev's at 4k and above = fun car. Otherwise it's a dog.

Hi John:

I should have been clearer in my last post RE: valve seals. The car shook something awful; it stuttered a bit, and then smoothed out and purred like a kitten after. After the seals where changed out, that went away.

Sorry for not being so specific.

The M103 engines are very notorious for valve seal problems.

M104 and M117 engines have virtually no problems with wearing out valve seals, except I suppose at extremely high mileage, and his car is just broken in.

If he had worn out valve seals, he'd likely find oil on his spark plugs, and be consuming oil internally.

I don't think valve seals are his problem.

My guess is either fuel delivery or vacuum.

I agree. It has to be a fuel supply / pressure problem or a very slight vacuum leak that is hard to find.

Remember, my terrible oscillating idle problem turned out to be a vacuum leak at the intake manifold seal, but it only occurred after the car had reached operating temperature.

How can check the intake manifold? By the time I remove the air cleaners, I don't think I want to spray carb cleaner around the intakes looking for a vacuum leak.

On my car, the airbox is to the left, and the intake manifold is on the right. Don't know how the V8 is set up.

However, you can just spray water at the intake manifold gasket. If the gasket is bad, you will get air bubbles.

I sure am glad you guys are talking about this subject as my 89 420 does the same thing but only slighly and about 10-20 seconds max. Then smooth as a whistle. Its a little annoying but not to the point of seriousness yet.

My mechanic told me its probably a leaky injector, but now I'm wondering as it hasn't been checked yet. With 105,00 miles I would think injectors would be O.K> but you never know.

Will keep up with your verdict. Thanks for the new light shed here.

Keith D

rough start
 

Correct me if I am wrong this only happens on cold starts right, if so did you check the cold start circuit. On the 117 engines there is an additional cold start injector to increase fuel volume for the initial start this goes away once up and running. Not sure if I am even close as I am unfamiliar with the newer post 92 engines.
hope this helps.
martin

I'm sure if there is a "cold start circuit" on this engine in '95; I'll check into that.

Assuming there is, let's figure this into the mix --- if I turn the ignition to key to "on" and wait 10 to 20 seconds before starting the engine, then rough starts don't occur (I think). Why "I think"? Because, sometimes the car kicks over just fine, other times it is this rough, rough start. The rough starts seem very random.

If was a circuit failing, I'd expect the results to be consistent and repeatable. This problem is more random (or at least seems that way since we don't know what the fault is). I'm not saying that the "cold start circuit" can't be the cause, it could be. What I am saying is, I would think the symptoms would be more consistent if the "cold start circuit" or some derivitive thereof because either the circuit is open or closed.

Yes, no???

As an aside to this; I went through records since I've had the car (purchase it with 68k miles) and the fuel filters have not been replaced. I told the shop to replace those. It's a cheap replacement, so we might as take those out of the equation a possible factor. FYI - the car has 96k miles on it.

Wow, your fuel filters should be changed every 30,000 miles. That could cause a restricted fuel supply problem.

Yeah, yeah, yeah... I know and ASSUMED they were changed at the 90k check up. It's alittle embarrassing to admit. If that is the problem - alot of money spent for no reason. I asked the shop to double check whether they replaced them or not at 90k service.

COLD STARTS
 

John, if you let the key stay on for a few seconds and then start without idle issues then I think you have found your problem. When you turn the ignition the fuel pump starts up and pressures the system if you start straight away it does not get the chance to pressure the system enough. I would agree with you on it not being the cold start system now. Another way to pressure on old cars is to turn the ignition a couple of times as the fuel pump only runs for a predefined number of seconds.
I would look into why you are losing the pressure. Which is where you are already. Sorry was not much help
martin

His fuel accumulator should be maintaining pressure in the system indefinitely. He wouldn't really need to put the key in the on position and wait for any interval of time at all.

If his system is not holding pressure overnight, then the problem would surely by the accumulator.

good point
 

good point suginami. So he has a leak after the accumulator as turning the fuel pump on repressurizes the system, or his accumulator is not holding the pressure.

Re: good point
 

That is my guess.

I'm not a technician, but I stayed at a Holiday Inn Express last night.

They are still working on the car but feel they have located the problem - the crank sensor. The tech tapped the connection point and the engine died. After playing around with alittle, they said the vibration went away, etc., etc. They didn't find any problems in the fuel pressure check.

So, that crank sensor wire/connection, whatever you want to call it is being replaced. They also recommended a new spark wire set; it has the original w/ 96k miles on the clock, so I might as well replace it. And of course, fuel filter replaced too.

I was worried that it might the timing chain - stretch or that the guide rails were chipping apart. It seemed alittle earlier for that, but I'll drop the car into 3rd and 2nd with out any hesitation while passing cars on the freeway. A quick 50 to 100 mph accerlation is always good :D :D :D :D

I should get the car back in a couple hours, so I'll post update this weekend after I've put the car through its paces.

Good good good.

I wonder what a crank sensor is. I've never heard of one.

I agree that it's a great idea to put it in a spark plug wire set and coil wire. Have you replaced your cap and rotor yet? I've read that these M119 engines are hard an caps and rotors. I usually replace cap, rotors, and wires in sets. In fact, I usually do plugs at the same time, too, for piece of mind.;)

Just car the back; no difference... errrggghhhh... It's going back Monday anyway because they didn't get the wire set on. That could the vibration at idle problem, but I would expect more dramatic problems.

The cap & rotors were replaced at the 90k service.

I think the crank sensor only plays a part during engine set-up, not sure though. It determines the position of the crank shaft; I've read about in one of the other posts here. I'll try starting it a couple different times after varying time intervals and see if the cold start issue is gone.

The crank sensor appears to have resolved the cold start issue; no rough starts in the last couple of days. However, the vibration in the steering wheel remains while the car idles. I'll update the original post as we sort through the vibration issue.

Hey John, if the vibration @ idle in the steering wheel ( presumably in "D" ) disappears in reverse, the engine mounts are no good. Try it out.

The vibration is in all gears. Anway, the motor mounts and transmission mount were already replaced.