When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
i dont think it would run without the coil working and i dont think they can become "weak".. but, thats an area im not sure of. . i was interesting that the bad coil wire that was replaced, didnt effect the issue. I mean, the connector internally, was broken and was only making contact by the rubber boot keeping it in position. also, it runs fine under load . but, in idle, any RPM shows the miss, so that also shows me its more fuel based, as the spark would get stronger with higher RPM and thats not changing anything. . the other thing im thinking , is cam timing. which looked to be changed by my markings , but the compression doesnt indicate any issues there.(could changed when i changed the timing belt/waterpump
im going to start it up cold right now, and see if the miss goes away...... if it does , it could be the fuel enrichment masking the issue...also, when it warms up, im going to pull the o2 sensor, to make it go closed loop and see if the richer mixture solves the miss.. if so, it could then be narrowed down to o2 sensor, or injector being lower flow than design, at part throttle.
i started it up, and it didnt miss for about 30 seconds, and then it started. i waited until the closed loop started going, (hunting of the mixture using the 02 sensor) and the misses didnt change. then, i pulled the 02 sensor to see if going rich, would change the missing.............it didnt. 12:1 fuel air, and it was still missing .
So, then i jacked up the rear of the car and did some load tests by riding the brakes. slight part throttle, curred the problem. no miss from 2000rpm to 4000rpm. it seems any additional fuel cures the problem. but its still worrisome because no one likes to hear "misses", even though this is a idle , or engine in very low throttle problem.
I'm thinking it is a fuel injector issue, so i might try some C-Foam. thoughts? take the injectors out and check them out?
One injector not delivering cleanly at low revs/load? Try pulling injectors one at a time to isolate which one it is. If that works, try to verify by pulling plugs one at a time. Swap the underperforming injector to another cylinder, see if the miss moves with it.
jp 83 Euro S AT 57k
I'm thinking it is a fuel injector issue, so i might try some C-Foam. thoughts? take the injectors out and check them out?
Mark,
My experience with the Bosch fuel injectors in my location is that they seem to foul up more than other makes and whereas I have no hard data backed up by many data points I have formed the opinion that these things need to be pulled, tested and u/s cleaned about every 60k miles or every 10 years. First time I did this was on the original injectors that had covered such mileage, On average the injectors were flowing 5% less than they should and the worst injector was flowing about 10% less than rated and the spray patterns were also compromised. To my surprise I found a specialist fuel injection repair shop locally with the appropriate test rig and u/s cleaning capability and they did the business for some $80 when US based outfits were charging circa $200.
Whether or not your injectors need cleaning remains to be seen but if they have not been tested in the last 10 years then it should be easy for you to get them tested and/or cleaned as necessary. As for proprietary injector cleaners like Techron I suspect they work to a point but in reality are better when used as a prophylactic measure by dumping a bottle in the tank and then filling with fuel once every 3 months or whatever works for you. If you do have them tested try to witness the process so that you can satisfy yourself that no corners are cut and that the results are genuine unless you know and trust the test house.
put a bottle of Techron in the tank do short drives so it has time to work
do you think that will do anything if they are showing the symptoms ive mentioned? is it better than Cfoam?
Originally Posted by jpitman2
One injector not delivering cleanly at low revs/load? Try pulling injectors one at a time to isolate which one it is. If that works, try to verify by pulling plugs one at a time. Swap the underperforming injector to another cylinder, see if the miss moves with it.
jp 83 Euro S AT 57k
it sounds like it, after all, the engine runs well at higher throttle levels, and certainly full throttle at all RPM. so, it sounds like it is more along the lines of a fuel issue,and that seems to point to an injector. because it is so intermittant, i wonder if it will be easy to spot... maybe all the injectors being pulled will make it worse, but one??? is that what i should expect to find?
Originally Posted by FredR
Mark,
My experience with the Bosch fuel injectors in my location is that they seem to foul up more than others
Whether or not your injectors need cleaning remains to be seen but if they have not been tested in the last 10 years then it should be easy for you to get them tested and/or cleaned as necessary. As for proprietary injector cleaners like Techron I suspect they work to a point but in reality are better when used as a prophylactic measure by dumping a bottle in the tank and then filling with fuel once every 3 months or whatever works for you. .
thanks fred. i tend to agree, as i cant imagine if there is a clog it can be dissolved by something diluted in the gas. but, i dont know! let me try the removal of each fuel injector connection and see if that shows anything. i did the plugs and that didnt do anything. each plug pull made the engine miss and then backfire when reconnected.
Guys, i just did some Seluthing to see if i could narrow down the issue. the miss is very inconsistant... and it is also non-existant from the first 30 seconds from a cold engine start. then, it starts to appear. I decided to start pulling injector wires, as the spark is not the same type of missfire. (and then backfire when its reconnected )
the sound of the miss when pullling an injector is distinct. so, when i pull #1 , the misfire is perfectly repeatable and in a even rithem. da da da da da da da da da da ..... almost has the tone of an exhausat leak click. THEN, i remove another injector (and i did this to the entire set of injectors). and the miss is perfectly spaced BUT with a random click,
da da da dadadaad da da dadadadd da da da da ddddaaaa da da da (like this sound)
that is the same as when they are all connected. this happens UNTIL i remove #1.. #1 injector being pulled gets rid of the randomness.
So, this is pointing to #1 injector being the culpret and seems to be ONLY an issue at idle, neutral power levels any thing part throttle and some moderate load and the car runs and accelerates fine as you can ear on the video.
so, maybe i try and run some techroline in the car for a tank or so and see if that helps. i guess i could pull the fuel rail and look but do ou think i would see anything if one of the ports were clogged ? if so, why are the plugs look exactly the same? could a clogged port restrict fuel to change the mixture much under wide open throttle? or maybe its got a clog that allows flow to dribble or not atomize so , it misses occasionally.
any other suggestions??? Here is the #1 plug..... looks like , exactly like 3 others i checked quickly today.
Originally Posted by Mrmerlin
put a bottle of Techron in the tank do short drives so it has time to work
First time I pulled my injectors for testing/cleaning on average they were down 5% on flow with one injector down 10%.
When did you last have the injectors tested/cleaned?
they havent been.. they were new with the new engine build.. so, 120 hours plus 10k-20kmiles street driving. you would figure a difference this substantial, would show up in the new plugs appearance during 2-3 hours of racing. the plugs all seem identical and there doesnt seem to be any power loss associated, but i havent gone to the dyno after this issue had appeared.
The stock amps. should i pull the covers to get the brand? what are you thinking?
thx
They are consumables so I change them when I do coils and wires. Have seen odd failures on them. Have had no luck with the cheap ones. Get some new Bosch amps and at least if they don't fix the problem you won't have to worry about them for 15-20 years.
07-21-2018, 02:18 AM
) 
