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gaara
New Member
2 Posts |
 Posted - Jun 06 2010 : 3:47:29 PM
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Hey man, so since you're the super genius I have a strange problem and need a little help. The car runs great, but I have hot start problems. I went ahead and checked compression, replaced the plugs, oil, and filter. The weird thing is that it fires right up, runs great and as soon as i turn it off, it won't turn over. The strange thing, is that I can push start it when it's hot and it starts right up. I thought maybe the starter was bad, but that wouldn't let it start cold. I checked to see that the starter lined up, and the bolts were stripped out, so we re-tapped them and the problem still exists. Any ideas?
(Edit...Move to RX-7) |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Jun 07 2010 : 09:38:50 AM
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Check the intake air temp sensor, and the engine coolant temp sensor.
Also, when is the last time the injectors were serviced? |
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gaara
New Member
2 Posts |
Posted - Jun 07 2010 : 11:16:17 AM
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| I don't know when the injectors were last serviced but I have to pull the UIM again tonight so I guess I can have the injectors cleaned when I got it off. Last night my buddy and I tried to replace the UIM with a jspec one from the same year, but there's not brake booster vaccuum (which didn't go over very well) and for some reason my idle bounces from about 1200-1500. So tonight I'll pull the UIM, clean the injectors, put the stock UIM back on and see what I got. I'll make sure to check the intake temp sensor and the coolant temp sensor. Thanks for the help and I'll keep you updated. |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Jun 07 2010 : 7:04:47 PM
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| The injectors must be cleaned by an injection shop. It's not something you can do. But leaking injectors are also a major cause of hot start issues so that is certainly something to try. |
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bunkman
New Member
1 Posts |
Posted - Jun 16 2010 : 10:14:31 PM
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| I am having this same issue on my 1994 RX7. I will check the sensors and the injectors. |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Nov 16 2011 : 6:34:35 PM
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Hey AC I have a similar hot start problem on My 1990 vert. but this did not happen till I changed back to my stock Fuel Pump ..the car has new injectors, new plugs, new water temp sensor, and new intake air sensor. the high flow fuel pump was causing a high fuel pressure issue that kept kicking an engine code and forcing the car to run rich and get terrible gas mileage. once I changed the pump It ran great and maintains a 14.5-14.7 ratio. the car also eventually gets hot (195-200) at idle and bumper to bumper traffic and I see the fuel pressure drop to 15 psi or lower plus the AFR gauge reads lean 15 ..16.17.18. before the car will eventually stop running.
why do you think the fuel pressure drops when it gets hot?
It only has the hot start when it it sits for more than 20 to 30 minutes. i use a fuel cut off switch to get by ..but sometimes it takes 10 minutes to start.
..I also noticed I cannot maintain fuel pressure in the line after shut down. does that mean the pump is bad ot the line is leaking?
is there a better way to install the fuel pump so it maintains pressure ..I got a used turbo two pump to try but have yet to install it. Love the Cosmo Videos!!! |
AL M GURDIAN |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Nov 19 2011 : 10:22:31 AM
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Fix your cooling system so that the car doesn't run hot:
http://www.aaroncake.net/rx-7/cooling.htm
Check the condition of the fuel pump wiring and relays. Check the voltage out of the alternator and have it load tested.
Hot start issues can also be caused by low compression. |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Nov 22 2011 : 07:39:55 AM
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Okay I do have an aluminum radiator and a 1800 cfm push fan to complement the stock fan clutch on the car. I reset the thermostat to kick on at 185 and now the car would not get hotter than 193 in traffic. the fuel pressure stayed more consistent too and the AFR stayed @ 15:1 so the car did not stall. Your link says its probably the fan clutch, So it's time for a 2800 cfm pull fan with shroud. does it matter if I do the compression test on a cold engine?
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AL M GURDIAN |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Nov 22 2011 : 07:51:10 AM
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| Hey AC on another note I recently completed a Megasquirt DIYPNP for the Rx7. I wanted to run the NA on it first and then use it for my fledging Turbo II project. this was supposed to be up and running by know but me and Tech support are not getting the job done. tech support said my construction of the unit was sound but there is no spark in the settings they say to use. Can I ship it to you to troubleshoot it? I can send the updated software as well on a memory stick? |
AL M GURDIAN |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Nov 26 2011 : 10:31:12 AM
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I won't be troubleshooting someone else's Megasquirt build. In the past this has not worked out well for me so I don't touch stuff like that anymore. If you have no spark and all the settings are correct, are you getting RPM? If so, then the CAS and VR circuit is properly configured so there is an issue with the ignition outputs (pullup resistors jumpered?) or the coil wiring.
You're going to want a fan of at least 3000CFM to be safe. Set the fan temp to 190. |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Nov 29 2011 : 09:18:18 AM
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Hey it was worth a shot ..I messed around with the DIYPNP and I did get spark in other settings ( the ford one) tech support says that does not matter and to go back to the original settings
tech support says I am losing RPM intermittently. back to the stock CPU ...I solved the hot start problem by putting a kill switch on the 1C pin out per Hailers recommendation. also ordered a simple voltage switch to do this automatically from now on. Such a smooth start up now I can hardly believe this is the same engine.
any ideas on how to maintain fuel pressure in the line after shut down?
as for the hot idle issue my new 2800 cfm fan matched with the 1800 cfm push fan should do the trick correct? |
AL M GURDIAN |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Dec 03 2011 : 10:38:11 AM
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Loosing RPM intermittently would indicate a noise problem with the CAS wiring. Is it all shielded cable, with the shield grounded only at the ECU end? Are both pots all the way counterclockwise?
Why bother with two fans? Just get a nice fan of around 300) CFM and use that. 2 fans are just going to overload the alternator, which is probably already struggling.
Line pressure should be maintained in the lines, so it's worth checking your FPR as per the factory instructions. |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Jan 08 2012 : 12:40:23 PM
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Hi AC I modded my stock fuel rail to eliminate the FPR. I set my Adjustable FPR to 17 psi and she is running very well to redline. goes right into close loop with no check engine light ( I am running new 550 injectors even though everyone says I should not ) )also checked my fuel pump and the connections were loose which I believe was the cause of pressure loss as she warnmed up. getting around 300 miles to the tankful. idles very smoothy now that the fuel pressure has been regulated lower. Two issues I'm dealing with now:
My car still wants to flood on cold start up now if im not careful and even though I clamped the hose on the fuel pump tightly ..she will not hold any fuel line pressure at all. when cold sometimes it seems to want to start on one rotor only then when I rev it to 3k it kicks in the second rotor. have you any experience with this? (I have a modded throttle body that eliminated the thermal pellet and the cold start up to 3k) |
AL M GURDIAN |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Jan 11 2012 : 09:17:53 AM
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Loosing RPM intermittently would indicate a noise problem with the CAS wiring. Is it all shielded cable, with the shield grounded only at the ECU end? Are both pots all the way counterclockwise? In reference to this question I have not changed any of the stock harness for the CAS ..and it runs great with the stock CPU ..I will check the POTs
thanks |
AL M GURDIAN |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Jan 11 2012 : 10:34:43 AM
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Something is VERY VERY wrong. 17 PSI?! That's WAY below the point at which the injectors will spray properly.
On a NA you should not be running 550CC injectors...they are way too large and will just cause the engine to run rich. There's part of your issue. You need to tune your VE table for the larger injectors. Don't play with fuel pressure. Set static pressure to 35 - 40 PSI.
The stock CAS wiring could be very noisy. Run a brand new shielded 4 conductor cable, grounding only at the ECU end. |
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AGURDI590
Apprentece
USA
19 Posts |
Posted - Jan 12 2012 : 08:00:33 AM
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| Well I've never been known to do it the conventional way. When Fuel Pressure is up past 22 PSI it wont idle smooth and runs so rich on the AFR Gauge. It also drops the 17 code which I thought was the O2 sensor ..But after replacing it 3 times I moved on to fuel pressure. The 550 injectors with lower pressure are not making the car run rich as it is dropping into close loop mode and getting decent mileage. I really appreciate all your help and will send my stock injectors in for an overhaul cleaning. Then maybe she will sort out and can be set to a higher pressure. In the mean time I am still wondering why I can't hold any line pressure. I can switch fuel pumps as I have a turbo 2 and a walbro I could put in ..isnt the check valve that holds the pressure built into the fuel pump? |
AL M GURDIAN |
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Topic |
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RX7 Turbo II Strange Hot Start
