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Here is the back of the UIM, you can see that the fast idle assembly is not aligned with the roller when the car is cold, and I have a video in the other thread that shows that it is not aligned even when the car is hot. Is this normal?
Those injectors look like 19550-2020s, which should be high impedance 550cc. Double check resistance on those injectors. If you get ~15ohms they're probably fine. If they're clogged you can send them out to get them cleaned. They'll put new pintle caps, grommets, and orings. its around 25usd per injector plus shipping. But since it was running before how could they be bad? That doesn't make sense. Did your mechanic say what was wrong with them? Maybe try running them and see what happens.
Also double check the resistance on the injectors you bought. They should be around 15ohms as well. You can access the secondaries without removing the intake manifolds.
Also, since the engine idles, spray carburetor or starter fluid around the engine while its idling and listen to the rpm. If the rpm speed changes then you have a vacuum leak.
Commentary:
Video 1: Fast Idle Assembly will not affect boost levels. It will change idle, and can be adjusted in a later step. Priority 1 is your big boost problem because if there is a boost/vac leak, it will alter your idle settings. Idle adjustments can't be made until the system is determined to be airtight (or close to it).
Video 2: Your AWS solenoid sitting on top must be addressed. It is in frame on top of your intake manifold in the second video at 1:36. It is attached to your intake and is intended to bypass intercooled air around your throttle body and into the intake to allow the computer to raise idle during cold operation to compliment that provided by the Fast Idle Assembly. In the video, there is no hose connecting the AWS solenoid to your post-intercooler piping. This solenoid is not made to hold a large pressure differential, such as manifold boost to atmosphere. It is meant to handle the pressure differential between intercooler pressure at idle and the manifold vacuum at idle. This could be a potential source for your problems as it is a sizable diameter orifice. The two solutions to this are a) run a hose from the AWS solenoid to the post-intercooler piping, closing the air circuit and retaining function of the AWS system, or b) remove and disconnect the AWS solenoid and cap the manifold port, eliminating the AWS function. This might not be the solution to your problems, but it is a significant problem to address.
Do the compressed air vacuum/boost leak test after performing the repair for the AWS. This should let you determine if the system is airtight or has a major leak. Beware of doing the vacuum leak check with combustibles as listed by FuhrerTuner. You would be spraying flammables in an engine bay that could be ignited from hot exhaust, or loose electrical connections. This type of test is better suited (still not a great idea) to natually aspirated engines as opposed to turbo engines because the entirety of a naturally aspirated intake is under vacuum. On turbo vehicles, any leaks in between the turbo compressor and the throttle plates are at near atmospheric pressure under idle conditions and can go undetected with a combustibles test.
If after conducting the leak test, the system holds air adequately, then we can get you through the process of setting hot idle, and the fast idle assembly. Let us know how it goes.
Hi all and thanks for your replies guys.
I have read your posts and I just wanna say that your help is really precious to me. I will check everything that you suggest and try to find that stupid monkey on my motor...
Right now, the whole Greece is under strict quarantine and we are not allowed to go out...just in case for food supply , short exercise or emergency situation. I am super busy trying to teach by teleconferences etc. The e-class platforms were not prepared for heavy use and we are trying to manage all this from our houses. The good thing is that the pandemic is going well here in Greece because of the really strict measures that had to be taken. Our public health care system would have collapsed if we had not taken these measures.
FuhrerTuner, my injectors were refurbished two times in the past and the engine had a hot start problem. Not a severe problem but sometimes the engine flooded and I thought that my injectors were leaking. That's why I thought to buy new ones.
Pyroman, I will do everything that you suggest and post an update.
Guys I do not know how the things are going in your area but try to stay at home and avoid contact with others as much as you can. Try to protect yourselves and your families.
Best wishes and just remember that we will ride again our 7s soon...
Good to hear you're still around. Hopefully you can get outside and get some fresh air soon. Not too bad here, just boredom. I've torn apart and refurbished all the small electronics projects I've had around the house, and am waiting for parts to finish.
Had a thought, also check your engine compression while you're at it. It would be good to know that the compression is still good. If you see your oil pressure rising with boost, that issue will take priority over whatever we have suggested here.
Those injectors look like 19550-2020s, which should be high impedance 550cc. Double check resistance on those injectors. If you get ~15ohms they're probably fine. If they're clogged you can send them out to get them cleaned. They'll put new pintle caps, grommets, and orings. its around 25usd per injector plus shipping. But since it was running before how could they be bad? That doesn't make sense. Did your mechanic say what was wrong with them? Maybe try running them and see what happens.
Also double check the resistance on the injectors you bought. They should be around 15ohms as well. You can access the secondaries without removing the intake manifolds.
Also, since the engine idles, spray carburetor or starter fluid around the engine while its idling and listen to the rpm. If the rpm speed changes then you have a vacuum leak.
Hi guys! The strict quarantine measures are almost over and I will try to continue the troubleshooting by checking the injector's resistance as FurerTunner suggests. I just want to ask if the 15ohms value is right? Is it 15 ohms indeed (seems low...), or 15 Kohms?
And I will spray all over again with some carb cleaner to check for vacuum leaks. Can I safely spray near the injectors to check if there is a leak in there? I mean, is it safe to spray directly to the injectors with the engine running?
Good to hear you're still around. Hopefully you can get outside and get some fresh air soon. Not too bad here, just boredom. I've torn apart and refurbished all the small electronics projects I've had around the house, and am waiting for parts to finish.
Had a thought, also check your engine compression while you're at it. It would be good to know that the compression is still good. If you see your oil pressure rising with boost, that issue will take priority over whatever we have suggested here.
Yes you are right Pyro, I have thought to check that too but I have to go to the mazda service shop in order to do that.
Previously you proposed to remove the UIM myself. Is it that easy indeed? Do you just follow the FSM instructions?
I forgot to mention that I have also bought a complete block off plate kit. I will try to tap the AWS as soon as possible! Should I also block anything else...just in case? Any suggestions?
I think looking into the injectors is definitely a worth while expedition, as a trained aircraft mechanic we are constantly tracing back to work that has previously been performed while troubleshooting, you should never assume a job was done correctly. I have recently undergone a S4 TII swap on my FC, so there may be some differences in electronics, however some of the principles will still apply. I had only recently gotten my Greddy Type-S BOV to function (was using the wrong vacuum source), and shortly after I had a weird part throttle issue, where only lightly feathering the throttle would cause the car to run very rich, 9.5-10.5 AFR, with a lot of backfiring, missing, hesitation, etc. If you increased the throttle a tiny bit more, it would run normally in the 11-13.0's AFR's under boost, 14's while cruising. I spent hours researching, did a boost leak check described above with no results, cleaned grounds, checked out most of my sensors, the coolant thermo switch behind the water pump (richens for cold starts, often causes hard starts, rich mixtures when bad), the TPS (causes bucking & hesitations under decel, more important on S5's with the full range capability), the MAP (very critical for turbo cars), the AFM (also very critical for any RX-7 not using stand alone ecu), IAT (richens mixture cold/retards timing hot), and O2 sensor (only affects the car during cruise to lean the mixture for fuel economy), and I didn't even consider the last thing I had worked on (the BOV) could be the cause. I finally decided to stiffen the spring pre-load on my BOV so it would not open anymore, and just like that, problem went away.
I believe my issue was actually under that specific condition, of near atmospheric pressures (not vacuum, not boost) created while feathering the throttle, paired with maybe too soft a spring pre-load, the BOV was actually slightly opening, causing a intake leak, the AFM was metering a set quantity of air, the ECU was delivering a preset amount of fuel for that quantity, but not all of the air was actually going into the engine, and a rich condition would occur. Now if I had recirculated the BOV and not vented it like a ricer, I wouldn't have had that issue. And maybe I need to revisit my spring pre-load and see if I can run it vented without that issue. BUT it still doesn't fix the fact that a vented BOV in a stock ECU will not account for the missing air that gets vented, so richness, and backfiring can be expected, especially during gear changes.
Now this may or may not be your issue, I'm just explaining what I had, and how I went about troubleshooting, and alot of the time, issues that follow shortly after new work was carried out, are usually connected to that work, I ignored it, and it took me hours chasing ghosts.
I would honestly look at the impedance as previously stated, the stock ECU's are very old, and cannot learn, they only respond to what they were pre-programmed to work in conjunction with, so if a injector is out slightly in resistance, the solenoid might take longer to react with the voltages provided, and not deliver the correct fuel amount. Also, another angle to consider, is the injector seals themselves, there are 4 seals on each injector. the top o-ring to seal in the fuel rail, the rubber spacer in between the fuel rail and the injector body to provide the clamping force, a rubber sealing grommet between the injector body, and the intake manifold (secondary)/rotor housing (primary), and a o-ring in the air-bleed diffuser that sits inside of the intake manifold.
The injector grommets that sit between the injector in the intake have been known to be the culprit of many weird issues, they may seal while the engine is cold, and not while hot, or vise versa, as well, there are 2 different styles. S4 grommets are cut square on the corners, S5 grommets have a slight chamfer (rounded edges) where it sits in the injector boss in the intake manifold. I old thread I found in my research for my BOV problem had a fellow, who had S4 grommets in a S5 intake manifold, and would get richness, bucking, hesitations, etc, while running hot. He was convinced it had to be the coolant thermo switch or IAT sensor. That thread was 3 or 4 pages long full of attempts at checking sensors, flow checking injectors (and re-using the old seals, bleh), cleaning grounds, checking ecu pins, replacing parts, etc. Finally he got it hot, and did the old-carb cleaner check around the injectors, and he found it.
So any time you do injectors, use new seals on everything, the rubber gets hard and brittle as it ages, and make sure you get the correct parts!
Thanks for your reply P_Lav.
Your comments are very informative. I have suspected that my BOV could be leaking and I removed it to check but could not find anything wrong with it. I will try to stiffen the valve by turning the screw that has on top of it.
I have used this greddy BOV that vents to the atmosphere with no problem for 10 years.
The specs of the injectors that I used are these:
- Genuine Part (fit Denso) - Direct fitment to top feed fuel rail.
- 550cc flow rate at 3 bar.
- Flow matched 4 piece set.
- 12 Month Warranty.
- High Impedance.
I am planning to buy an air compressor and check for vacuum leaks with the method that Pyroman suggested. I tried to do that with the carb cleaner method but I think that I messed that up...Pyroman knows...
Thanks for your reply P_Lav.
Your comments are very informative. I have suspected that my BOV could be leaking and I removed it to check but could not find anything wrong with it. I will try to stiffen the valve by turning the screw that has on top of it.
I have used this greddy BOV that vents to the atmosphere with no problem for 10 years.
The specs of the injectors that I used are these:
- Genuine Part (fit Denso) - Direct fitment to top feed fuel rail.
- 550cc flow rate at 3 bar.
- Flow matched 4 piece set.
- 12 Month Warranty.
- High Impedance.
I am planning to buy an air compressor and check for vacuum leaks with the method that Pyroman suggested. I tried to do that with the carb cleaner method but I think that I messed that up...Pyroman knows...
I hate to jump back on the injector train but....
You should also measure the distance from the bottom of the fuel injector grommet to the center of the oring. OEM is ~63.5mm. IIRC Bosch EV14 long style injectors are 60mm, which could potentially cause an air leak.
Also again about the 550cc at 3 bar; Stock FCs run around 2.5 bar putting you at around 475cc.
I really want to remove the upper intake and check the injectors but I still don't know how to do that. For now I will buy a small air compressor and try to check for vaccuum leaks by using the method that Pyroman suggested. I will also try to remove the BAC and the AWS valves.
Also I contacted the ebay shop that sells them and he insist that the injectors are proper for S5 turbos. He also send me this...
Just an update.
I used Pyroman's method and checked for vacuum leaks by pumping air in the vacuum line that the boost sensor goes which is this one.
I found out that there is a vacuum leak for sure since the system could not hold any pressure at all. I can hear a sshhhh sound under the UIM and now I want to remove it and check there.
Also I removed the BAC and AWS valves and covered the holes with a block off plate (BAC valve) and a tapped silicon hose (AWS valve). Here is a photo.
I could hear the hissing sound before I removed the valves and also after that so I guess the UIM leak is certain, right?
I drove the car around the block and realized that now it has some hot start problems, the idle is weak and often dies.
While I drove I started to hear a rattling/knocking sound coming from the catalyst converter. \
I went to a local exhaust service shop and found out that the catalyst was broken. I had a spare catalyst and replaced it. Here is a photo of the broken piece of the old one.
There you go, the vacuum leak from the lines or injectors is most likely the problem, but its also possible you could have blew a line off while testing. Make sure you throw some small zip ties on those vacuum lines to keep them on.
There you go, the vacuum leak from the lines or injectors is most likely the problem, but its also possible you could have blew a line off while testing. Make sure you throw some small zip ties on those vacuum lines to keep them on.
Yeah I will certainly do that when I remove the UIM. Do you think that the turbo oil leak is serious? Any idea what it might leaks down there?
Assuming the injectors are properly sealed to the intake/fuel rails (which I am not.)
Injectors aside, I wonder if there is a vacuum/boost leak somewhere on the lower intake manifold. It may be smart to replace the LIM to engine gasket "while you're in there."
The only problem with this is replacing the LIM gasket assumes it can be:
1. Done properly with an MLS gasket and clean sealing surfaces.
2. Done without creating any new issues.
The above can be tedious, time consuming, and potentially expensive. LIM gasket replacement WILL be more expensive though if the injectors were not the issue this whole time and this gasket is overlooked.
I am not saying ignore the injectors as a possible issue; the above arguments are very valid to that end. However, do not rule out the LIM gasket until you've removed it and verified it's servicable. I've been guilty of this error in the past with a similar problem and thats my only reason for this post.
Assuming the injectors are properly sealed to the intake/fuel rails (which I am not.)
Injectors aside, I wonder if there is a vacuum/boost leak somewhere on the lower intake manifold. It may be smart to replace the LIM to engine gasket "while you're in there."
The only problem with this is replacing the LIM gasket assumes it can be:
1. Done properly with an MLS gasket and clean sealing surfaces.
2. Done without creating any new issues.
The above can be tedious, time consuming, and potentially expensive. LIM gasket replacement WILL be more expensive though if the injectors were not the issue this whole time and this gasket is overlooked.
I am not saying ignore the injectors as a possible issue; the above arguments are very valid to that end. However, do not rule out the LIM gasket until you've removed it and verified it's servicable. I've been guilty of this error in the past with a similar problem and thats my only reason for this post.
Thank you for your reply. When I replaced the injectors I had also bought the UIM gasket and the LIM gasket but the mechanic did not bother to remove or check the LIM gasket. He also did not change the UIM gasket and he used the old one because he said that it was ok. I was not present when he replaced the injectors. I just went there when he had finished the job. When I told him about the problem he said that if there was a vacuum leak from the gaskets the car would had the problem all the time.
03-22-20, 12:39 PM
