Over a couple weeks the car would more and more often not want to start up. Basically it would crank over just fine but then it would "kick in to idle", and it would just stop immediately after I stop cranking.

So I do a bit of research and hear a lot about flooding. Ok. But the car isn't totally flooding, I can get the car to start basically everytime I want to, it just is never nearly as easy as it should be. Often what works is just holding down the gas pedal, then it will backfire a bit and then drop into idle.

I had a conversation with a guy on FB about this and he said his fuel injectors were leaking. I forget if he specified how he knew but a lot of what he described was happening to him is what is happening to me. Basically I want to get some more thoughts or ideas before I go tearing the UIM off (AGAIN) to pull the injectors.

To get a better idea of the circumstances, here's the run down:
-90% of the time the car won't start and I'll have to go through the process I explained earlier, 10% it will start just like normal
-after it finally is started, it may idle a bit weird for a minute but will run and drive perfectly normal, no hesitation, misfiring or anything
-I do suspect my mileage is a bit worse than usual BUT I can't say for certain as I haven't driven the car like this for long enough to really tell-I just changed the spark plugs as of TODAY so they are totally new and it's still happening
-there hasn't been any loss of coolant or white smoke in the exhaust or increased temps that would make me think it has a blown coolant seal
-back in april I took the UIM off to replace a cracked HP fuel line from the primary fuel rail to the secondary fuel rail, as well as some other things and when doing so I removed the secondary fuel rail and then put it back in without adding or removing anything
-engine is a crate motor, put in 4 years ago and to my knowledge, reused many MANY of the original parts, presumably injectors included, and it has about 15-16k miles on it

I am pretty sure it's leaky injectors but id rather be close to certain. I know it's a lot but all help is appreciated, I really don't feel like removing the UIM in this California heat but if I do then atleast I'll be more sure than I was based on my own judgement. Thanks guys

 

My leaky injector symptoms:
- Harder start after letting it sit, had to crank for 3-5 seconds
- Instant smooth start if hot
- Hesitates a bit for 10-15s after a cold start
- Substantial amount of light smoke on cold start (was in fairly cold weather), fuel smell out the back

Had the injectors cleaned, problem solved. From what you described, I would be looking at the injectors too.

 

How did you go about getting the injectors cleaned? I have been told but others not to mess with the injectors themselves too much since they are very fragile.

 

Sent them off to a specialist shop for ultrasonic cleaning and flow/pattern testing. The injectors themselves aren't really fragile, just be careful when removing the rail. Easier to get the whole rail out with the injectors still in it than trying to leave them in place. Pull them out straight upwards (you'll need to get the fuel hoses off first), the fragile bits are the diffusers under the injectors. I would not try removing those, you can check if they are clogged, and if they are try cleaning them with alcohol in-place without touching them much.

 

I had mine cleaned by these guys
RC Fuel Injection
But there are other people out there.

 

I had a similar problem of hard to start when my car was cold.

A leaky injector to outside air can cause an air rich environment and sometimes you can see the evidence with a stain on the intake manifold.

Air rich can cause backfires.

I'd replace the water temp sensor behind the water pump plate. Backside of the alternator. The fact that hot and cold starts are different is a yellow flag.

Then I would change the seals on the injectors. The trailing are easy to deal with.

When they were out, I would look at the injectors tips. and look for signs of burning at the tip.

Also look at the diffusers and if they come out, change the o-rings.








If your air diffusers come out easily take them out. . . . .If they are stuck in, don't mess with it unless you want to buy a new one.







.

look at the injector pintle.







five o motorsports.

 

thank you man! thats super useful.
I was also wondering though could it be related to tps? I just replaced the module since it went bad but things starting having problems after I messed with the screw on top trying to raise the idle (the car was idling shaky and low because of the bad tps but I didnt know that) and I didnt adjust anything else.

 

Your best friend will be the emissions section of the field service manual.

http://www.foxed.ca/rx7manual/manual...SYSTEMS_NA.pdf

It has a section on setting the idle and adjusting the TPS.

You should probably remove the EGR valve and blank it off if it is not gone already.

Hope this helps. ..


Back probing the TPS connector to set the voltage of the TPS while the key is on.. . .twist the screw on the linkage and see the voltage.


Checking the resistance of the BACV


Checking resistance of low impedance injector



showing how to get the wire off the water sensor connector



resistance of new water temp sensor.

 

Alright, so I went through the idle set as best I could and nothing changed. So I pulled the secondary fuel rail to check out the injectors. This is what they look like:

This one is decently clean aside from the brown.

This one has some black carbon build up.

This is the air bleed for the one with the carbon on it. It was loosely in the injector hole as the o ring on it is completely done. The other air bleed is firmly in place so I didn't try to remove it.

Could the air bleed not be working and causing an issue?
Also, I wanted to get new injectors from FiveO and found high imp 460cc injectors that match these but are all 4 injectors the same?

 

Your injectors look good at the tip. .. .Doesn't mean they spray right, just means the seal looks to be good.

Blank off the EGR while you are down there.. . They sell kits. . ..plug the vac line to it.

Verify that the vacuum spider/vacuum line supplying vacuum to the oil injectors (large line from the UIM) does not leak.. . might need hand vacuum pump

Look around the leading injectors to see if you have blow back leakage or signs of gasoline stains.

The air diffuser that came out easily needs to have a new o-ring. It came out easily because the o-ring is old and dry. This will cause an internal leak but is probably not the source of the bad idle by itself

Last time I was down there on mine, I replaced the oil injectors.

Change the O2 sensor if you can.. . Its cheap to get a Bosch unit.

Definitely change the water temp sensor while you are there.. . It is also inexpensive to replace.

Be extra cautious when getting the intake snorkel back on so that it seals good to the aluminum intake manifold (DVI)

Start changing vacuum lines to silicon if you can. . silicon line is cheap. . .. always twist it off a plastic nipple never simply pull it off.

If you get it back together and it still has a bad idle, use the starting fluid trick. . . .. . When the car is idling, spray a little starting fluid on select parts you think might be a leak to outside air. If it leaks and sucks in starting fluid, the RPM's will noticeably change and go up for a second, or the idle will smooth out. . . . .

If you did all that and it still doesn't idle right, and you know you don't have a leak to outside air, that's when I would replace the mass air meter (and maybe the air pump).. . . I'd also change the check valve behind the air control valve. (this by itself is also cheap to do).