Hot idle issues

[Tjp8]

Hello guys , been driving the rx7 alot recently and just last week started having issues while hot idling.

When cold the car will idle perfect right up to temp, then the fans come on and after they havr finished cooling the car down it starts to splutter and run rough.


Ive changed the plugs, leads and coilpacks again today as i thought it would be ignition related.


The Engine has done around 4k-6k miles, high flow cat, mapped at 1 bar by jaydee and stu, intakes full exhaust,

Not using or losing oil or coolant either.

Its weird because it drives and runs brilliant until up to temp or after the fans have done one cycle then sounds like a one rotor , real lumpy and shit.


Not sure what to look at next, anyone have any ideas?

 

[jdmr_neil]

Fuel pump, fuel pump relay, if you have a gauge on your fpr bridge gnd and fp in the diagnostic box and check fuel pressure.

I had this same thing and it was the fuel pump (044) dying.

I had a video on here showing my fpr guage bouncing about when it should be 42 psi solid

 

[Tjp8]

Fuel pump, fuel pump relay, if you have a gauge on your fpr bridge gnd and fp in the diagnostic box and check fuel pressure.

I had this same thing and it was the fuel pump (044) dying.

I had a video on here showing my fpr guage bouncing about when it should be 42 psi solid

Its got fuel the rear plugs were real wet when i removed them, and ive recently refreshed the fuel pump , sock, and filter, too,i have standard fpr not too sure how to test this


Would a coolant temp sensor throw the idle out when hot? , or an iat sensor ?

 

[Tjp8]

Changed the coolant temp sensor for one i bought a few months ago and no difference to idle.

 

[jdmr_neil]

Have you recently done the fuel pump mod that bypasses the resistor and put a constant 12v?

Sounds like the hot idle is dumping fuel in.

Injectors next, a primary could be stuck. Cleaning is around £30-40 iirc

Other than that give the experts a shout, are you on a pfc or another ecu?

 

[Tjp8]

Have you recently done the fuel pump mod that bypasses the resistor and put a constant 12v?

Sounds like the hot idle is dumping fuel in.

Injectors next, a primary could be stuck. Cleaning is around £30-40 iirc

Other than that give the experts a shout, are you on a pfc or another ecu?

Im on pfc but not got the comander,

Fuel system is stock except quantum 340 pump.

I did have an issue a few months ago where the fuel sock was filled solid with rust and i had to change it then clean and refresh the fuel tank .

Il see if i can find someone local to clean and test the injectors.

Thanks for yout help , i will report back with the updates

 

[jdmr_neil]

I know he is permanently busy but if your close enough to pop in and see Jay he will probably narrow it down in a few minutes with a wideband.

It sounds like something is failing but it's certainly worth getting a commander and a wideband if your keeping the car longer term.

 

[jdmr_neil]

Have a quick look to check the thermowax on the rear of the tb is working ok. Iirc it should be fully extended when warm.

Maybe worth take the iacv off and giving it a quick clean as it's only a 5 min job. It's mounted to the uim next to the firewall.

 

[Ceylon]

My guess would be a solenoid failing when hot which is fairly common when they go. Had this on one of mine, would really struggle to idle when hot.

 

[Tjp8]

My guess would be a solenoid failing when hot which is fairly common when they go.

I run a simplified rats nest , do you mean one on there could be faulty?

I did see something online about the one near the back if the engine that controls fuel or something, il give them a test and see if they are ok

 

[Ceylon]

Yeah, the solenoids often pass a cold test but fail a hot test. I wrap them in foil and heat them in the oven for testing.

 

[Tjp8]

Ok so i tested all the solenoids hot and cold and they all work fine, i took the icv out and had a look at that it was fine, i took the idle air temp sensor out and gave it a wipe and put it together and now its running fine hot and cold.

I drove it round the block did a few revs , let it do 4 radiator fan cycles , so the car was well up to temp and cooled down a few times and still no issues.

Weird cos i didnt change anything.

I got the solenoids well hot to test them too so god knows what this issue is.

I will start the car again tomorrow morning and see if its still running good.

 

[jdmr_neil]

Sounds like just a shit connection somewhere and you disturbed it which in turn sorted it for now. My guess would be the icv as that plug gets warm, collects shit and never gets moved.

 

[Tjp8]

I did wire brush all the connections to the solenoids as they were a bit gummed up too, , some of the wries to look a bit cracked where the connectors attach ,

isit ok if i just cut the end off and soldier new wire on and this not cause any issues ?

 

[Tjp8]

Turned car on this morning , idling perfect, did a fan cycle and still fine, drove 30 miles with mixed driving , did few hard pulls and a few stops at traffic lights, so i know the car was fully hot and no issues.

Brought the car home and let it idle till the fans come on and still fine.

How strange.

 

[jdmr_neil]

Turned car on this morning , idling perfect, did a fan cycle and still fine, drove 30 miles with mixed driving , did few hard pulls and a few stops at traffic lights, so i know the car was fully hot and no issues.

Brought the car home and let it idle till the fans come on and still fine.

How strange.

Fixed mate, dodgy connection. Not always so easy to find so chalk that up as a bonus win!