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Discussion Starter #1
Been trying to solve a hot start issue for years and finally have a starting point. The issue is when the engine is hot and you start it after letting it set for 15 mins or so it has a rough idle for 10-15 secs then clears up or dies. I discovered today that when this happens if you remove the vacuum hose that runs from the IAC to the fuel regulator it clears up. Any thoughts?
Thanks,
Rusty

FYI 1995 RRC 3.9
 

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by disconnecting said hose, you are introducing false air to the possible rich mixture. this allows for proper / better combustion mix. if you have diagnosis software you could look at sensor functions on real life, among other important components on any fuel injection system you need to look into coolant temp sensor for loose or failed connector, failed sensor, static fuel pressure and 02 sensor activity when hot.

basically you may be experiencing a flooding hot engine.
 

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I am dealing with same issue on my '95. It happens only after longer highway drive. I was thinking leaking injector or two making the spark plugs wet, but that should be happening all time. It passing "smog test" fine!
 

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Thanks for the info 95classiclwb . I’ve replaced the fuel temp, coolant temp and 02 sensors and fuel pump/filter. I’m going to try this weekend to test the wiring leading from the sensors to the ecu to see if that may be the problem. I’ll post results. Thanks!
 

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Discussion Starter #6
Well I’ve checked the fuel temp and coolant temp sensors and both are with parameters. It’s definitely a heat issue because in the winter I rarely have this happen. Could the MAF have anything to do with it? Thanks for all the help,
Rusty
 

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Discussion Starter #7
If you ever figure it out please let me know. I’ve tried everything that I know to do with no success.
Thanks,
Rusty
 

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Rusty. I agree with you! It never happens in winter.All my sensors check within the parameters, fuel pressure right on. Just passed Colorado emission test fine. I swapped ECU before... no difference. I may attempt to get it hot and when it happens again, take all spark plugs out, to see which one is wet and clean the fuel injector (s). But it usually happens somewhere on parking lot.
Lets stay in touch, maybe we will figure this out.
Eugene
 

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I’m glad I read your post. I was thinking about ordering an ECU and trying that route. If I come up with something I’ll let you know. Good Luck!
 

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One more thing my Rover does. In the winter or when it is pretty cold I have a "dead spot" in gas pedal and it sometimes stalls. I am thinking Throttle positioning sensor is causing it. Could it be that is gives wrong signal to ECU when is hot weather? I do not have a spare to test it. With multi meter testing, it has a smooth curve but it depends how tight are the screws holding it in place.
 

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Discussion Starter #11
Update. Just discovered that when I had my distributor replaced the mechanic bypassed the ignition module that was mounted at the coil (conversion for heat) and relocated it back on the distributor. Could this be a cause of the hot start issue? Thanks
 

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I'd doubt it would give hot start issue.

Thoughts about amplifier location relate to durability of components it's generally presented as. Amp just has to switch coil for HT, so if it does that then it's working correctly.

Have you any hot condition compression test results for it? It may at least give you a combustion condition baseline to understand. Compromised pressure usually doesn't help hot start efficiency.

What plugs are fitted? And what gap are they set too?
 

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Discussion Starter #13
No hot compression test. Used champion plugs and not sure on gap setting. What do you recommend on gap setting? At this point I’ll try anything. Thanks
 

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In my experience they need to be kept at their minimum spec setting, many advise to increase the gap which I don't feel helps.
 

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Update. Just discovered that when I had my distributor replaced the mechanic bypassed the ignition module that was mounted at the coil (conversion for heat) and relocated it back on the distributor. Could this be a cause of the hot start issue? Thanks
Several of these items have already been discussed; however, I would recommend the following:


  • Remove and clean the ICV - spray cleaner into the plenum where the valve seats.
Reinstall the ICV with pipe tread tape and a paper gasket.You may try adding an additional paper gasket if you are running an inexpensive GM ICV – I have found the plunger length to vary.


  • Reinstall the ignition amplifier to its original position. I have found them to heatsink and produce a degraded spark when overheated and old. The truck will stumble about, and struggle to maintain idle/ignition – will smell like it is running very rich too.
I would address these items separately – I never like to change more than one variable at a time when sorting an issue.
My money is on the ignition amplifier….

Thanks,

Chris
 

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Discussion Starter #18
Good morning, just want to give you an update on the hot start and overheating issue that has just recently occurred.
I was able to fix most of the hot start issue by switching to non-ethanol gas. I thought that was odd since the vehicle should be able to run on ethanol. So after I thought I solved the issue, the Rover curse took over and the engine started to overheat randomly after 45 minutes of driving.
After several curse word and a trip to EBAY to see what I could sell it for, I decided to walk back from the ledge and try and fix It.
I decided to replace the radiator, fan, fan clutch and water pump. I know I committed a rover sin by replacing more than one part at a time, but frustration took over.
I am now pleased to report that the overheating issue is solved and it runs on ethanol gas once more.
Go figure... have thoughts on why but I’m an idiot and wouldn’t want to confirm that in a Text
 
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