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Joe's '91 405 Mi16 (and '90 SW and '92 Mi16)...


91MR2

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7 hours ago, 91MR2 said:

OK guys another interesting update…

I came over to my garage this morning and fired up the car, and it started very nicely, went through what seemed like a normal cold start sequence, and also idled very nicely, so these are very encouraging things. Here's the confusing thing. I went to check the codes again because I still have a check engine light, but this is what happened. Bear in mind I was having my mother help me by releasing the ground and we may have not done it properly. The car never went through the one-two sequence to show test ready, but it kept giving me codes 91, 92, 93. These codes aren't even on the sheet. Any thoughts?

I should also add that the idle air control valve was making some clicking noises while doing this test sequence… I don't recall this happening before…

Did you get code 11 and code 12, one was for starting to read the codes, other is for ending the reading process. Also you may need to clear the codes from the ecu, by keeping the wire grounded for 30 seconds.

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43 minutes ago, Goce said:

Did you get code 11 and code 12, one was for starting to read the codes, other is for ending the reading process. Also you may need to clear the codes from the ecu, by keeping the wire grounded for 30 seconds.

No I did not get either of those codes and that is what was so confusing...

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Another driving update, I went to take the car for a ride last night, similar to the night before, and it took a few cranks to get it to start and it idled quite poorly for the beginning,  and did not go through the proper coldstart sequence. Also had a few stumbles for the first 20 minutes of driving, but again after that it smoothed out and ran very nicely.

Again, this seems like a fuel issue to me, but would love other input. I ordered a new fuel filter and will install when it arrives, but I am wondering if I should also order 4 new Bosch injectors and a fuel pump to be safe. Thoughts?

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Sounds more like oil on spark plugs or dirty injectors, getting the fuel injectors ultrasonic clean is simple enough, the Mi 16 engine has the most accessible fuel injectors ever, 3x 10mm bolts and they come out. Try that first, Savo, has some experience and few contacts of places that do ultrasonic cleaning and flow testing on petrol injectors.

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 Also, I'm not opposed to having the injectors cleaned, however Bosch injectors are 30 bucks each on rock auto, seems like a good idea to maybe just start with new ones, and then I could still have a backup set, maybe get them cleaned down the road at some point? 

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Where i leave we have lots of bosch knock off, and they don't work at all, i've had so many new out of the box injectors stuck open or not flow that had me chasing my tail, with getting the injectors flow tested you know that they are working correctly.

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Most common problem with old engines is leaking oil valve seals, once the engine cools down the oil in the head leaks down the intake and exhaust valves and gets sucked and combasted on startup, that fails the spark plug, driving it the plugs get real hot and burn it off.

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I had a a problem with my car being hard to start; the solution ended up being a loose connection on the ignition module. I cleaned the connection and replaced it with a new one out of an abundance of caution, it's documented on my thread.

in my case, the car was harder and harder to start until it wouldn't start at all. I don't think it was running roughly once it did start, but it's possible that your problem could be an intermittent connection somewhere.

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Goce/Mike, not sure how to verify, but maybe rockauto is just trying to dump them?

Andre, I doubt that is my issue but will check the connection later tonight...

How hard is it to do valve seals on these motors? Does the head need to come off?

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Do you have a fuel pressure tester?  A dodgey FPR could cause running issues.  New injectors would be great if they’re indeed OE, and there’s a 5% code in our vendor section as well.  There’s a risk they could be knock off but they’re a discount warehouse so I’d bet on them just getting blown out.

Valve seals - tell tale sign is blowing blue on start up, and only after sitting a while.  It’d have to be very blue to start fouling plugs with oil.

Rabin

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Hi Rabin, I do not have a fuel pressure tester, however can get access to one if needed. Regarding the fuel pressure regulator, it was replaced a couple weeks ago, it was a cheap part so I figured why not. The car actually ran flawlessly today. Again, I keep going back to fuel as what I suspect is the main culprit here.  I just put in another 10 gallons of non-ethanol high-octane fuel this evening, and it just keeps running better and better. I'm not confident enough yet to say I am out of the woods with everything here, but I'm going to continue to drive it, and continue to run fuel through the system, it seems like that castle fireball actually helped out a lot.

I still have the check engine light coming on and off throughout my drives, but again the light seems to only really come on when the car is under very light throttle or when you are coming up to a stop sign or stop light, when you are driving under any kind of load, the light is off pretty much all the time.

Either way, I will take this as my only problem for the day… That of course, and my unbelievably rattly sunroof mechanism… This is driving me insane…

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it's been awhile since i've daily driven mi16, but as i remember, the ecu is making correction to the fuel map only when idling, and sometimes turns on the check engine, and stores code No: 31 if i remember right. But you seem to be on the right track, keep driving it, use good fuel. One question, are you getting krakel, backfires on deceleration from high RPM.?

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Goce, funny you should ask about popping/crackle on decel - when the car is running bad, in that it has the stumbling, etc., the popping is quite noticeable. When the car is running well, it is not nearly as pronounced. Still hear little ones, but you can tell when it is running poorly that more unburned fuel is getting into the exhaust.

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AFM is a good tip to check - Should be able to measure resistance as the door sweeps to ensure it’s nice and linear.

You could also test the injectors have a nice spray pattern by pulling them and firing them into glass jars, although for the money new ones seem like money well spent.

Rabin

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I'm asking because i'm suspecting over fueling, by your description you have too much fuel, ether sticking injector, or worn out AFM. The AFM, can't be easily checked, they are sealed unit, with a screw for small adjustment on the air/ fuel mixture. Only real way i know is to change it with a good used one or new one, search it by the bosch part number, the same part is used in many vehicles and there is NOS parts for as little as 20$. But i'll definitely do something about the fuel injectors. This is one instance where i've had almost no issues, because my car has two separate fuel systems, i've been running LPG on that car for long time.

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Goce,  thank you for the suggestion. I took the photos, just have to upload them later, will post them shortly. I am leaning towards just buying a new AFM though, because like you said, they are tough to read. Also, noted on the injectors, I am still planning to purchase the new ones and then also send my old ones out to be cleaned.

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No idea what the availability is for new VAF style meters are - but another option would be to do a VAF to MAF conversion:

 https://splitsec.com/wp-content/uploads/technotes/TN2_AFM_to_MAF_Conversion.pdf

There’s a few options for the conversion, but still no where near as simple as finding a new VAF.

Rabin

 

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Hi Bean, thanks for the suggestion, I'll read up on that.

Here are some photos of my afm. Looks ok to me, but I'm not exactly sure what I'm looking at. Again, CEL come on and off throughout driving, mostly on when under decel or approaching stop/red light and often while idling, almost never on under regular or heavy load...

 

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Bit hard to see at the pictures, but if there's white ceramic visible, then that part is worn out. For testing purposes you can write some pencil graphite on the white spots.

There are some guides in Internet how to repair the AFM. Easisest way is to bend the wiper contact to unused part of the track.

For a start you can gently clean the track with some electronic cleaner spray and white cotton swab.

 

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Hey guys, another update...

Drove the car another 80 or so miles this evening, it continues to run flawlessly now, for probably the 5th or 6th day in a row now. This is most excellent. A couple theories on this one as to why...

Mainly, I think I had some bad fuel, and with the Castle Fireball and a whole bunch of running (at least 3-400 miles in the last week), I think it is safe to say it has worked it's way through the system and worked some magic... 

Next theory is a little out there, but hear me out. While doing all the work over the last few months, the handle on the oil dipstick kind of deteriorated and fell off. No problem, we made a new one, nothing fancy, but it works just fine. Here's where it gets interesting. Ever since all this work has been done, the car was leaving a little oil on the ground, whereas before the car never leaked anything. I'm wondering if the oil may have been a little overfilled (due to the marker points on the dipstick maybe not being completely accurate now if the dipstick may be a little lower in the sump than before?), and maybe worked it's way through the came seals (the oil was always on the timing belt side). Funny thing is over the last few days, the car has no longer been leaking anything on the ground, and all has been well on the car. I'm thinking it is possible that if the oil was a little overfilled, it could have blown by the ring gap and eventually got to the plugs, hence causing my fouling/stuttering. I know this is a wild theory, but it seems plausible???

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  • 91MR2 changed the title to Joe's '91 405 Mi16 (and '90 SW and '92 Mi16)...

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