V8 starting problem when hot

[Walter Lotus 1]

Hi everybody.

I'm new on this forum but I'm driving Lotus cars for at least 10 years now.

My recent Lotus now is a V8 '99 .

It makes me crazy.

When the engine is cold it cranks up immediatly but when it reaches more than 80

[superdavelotus 124]

Hi Walter,

The first thing I would have changed (assuming that I had no engine check light on) would be temperature sensor on engine block. This is normally the culprit. after that coild packs but I would have thought you would intermittant drving faults too!

Try the above and if this doesn't work then come back to me.

Regards,

Dave Walters

[redshift 32]

Do you mean that there are 2 sensors?

One for the gauge and one for the ECU?

[talon 0]

Mine does the same thing, only I have a bit more slack in that it won't restart if it is over 97 degrees or so. I'm dropping it off today to have it looked at and will let you know what they find.

[hasuSan 0]

Yep! someone suggested to check your coolant temp sensor.

Also check if any of the injectors are leaking. When the car is hot and if any of the

injectors are leaking, it will dump fuel in the cylinder. It will be hard to start the car.... you have to wait.

The fuel will dissapate overtime. It will be easy to start the car.

[Paula&Marcus 0]

Hi All,

Yes, it might be a temp sensor, not necesserilay the coolant temp sensor, could also be one of the other temp sensors. Please check for plausibility with an OBD-2 scanner or Tech-1.

Yes, it also could be a leaking injector. The secondary injectors are known for bad O-rings and leaking. Please check both secondary injectors and have a close look at the inner O-rings.

A very easy and quick first check is to unscrew the holding bracket a little bit after about 1 hour when you have stopped the engine. If fuel is coming out under pressure, this will tell you that it is not leaking (much).

Cheers

Marcus

[mike_sekinger 694]

There is a special TPS triggered ECU procedure to clearing a flodded engine - maybe you can try this to see if it is likely to be a

[Walter Lotus 1]

I've got new fuel injectors and my mechanic will place them this week.

I will keep you'll informed if they solved the problem,

Thanks in advance guy's

Edited May 9, 2008 by Walter Lotus

[BobG 0]

Hi Walter, did you ever get to a definitive answer on this?

I have just started having the beginnings of the same problem, the "throttle down for a few seconds" procedure, in my case appears to improve things but not fully.

Cheers

Bob

[jcbjs 260 0]

Hi,still no answers back if anyone ever got this problem sorted. My car has this problem as well for some time now,starts perfect when cold but when warm/hot very hard to start(5-10 sec.cranking) before it fires up. Also runs perfect when driving. I have changed the temp sensor(ecu) but it remains the same. If anyone sorted this problem out please would you forward some answers. thanks

[talon 0]

You might try the crank trigger. If it gets flaky, it won't send the ECU the correct signal to fire.

[97-Esprit V8 0]

I had a problem with my car on hot starts, I found the solution was to replace the secondary injector seals, a mid '90s Chevy S10 pickup truck uses these as TBI's. Local parts store had them in stock.

Easy to swap (15mins) and problem was gone. I still do have a very hot starting issue, but if I shut the car off below 90 deg C it will start up just fine.

Another issue could be the fuel pump check valve, I am going to re-do my plastic fuel lines in braided steel and add an external check valve on the supply side.

Also the temp sensor may be the problem in my car, I will get a scanner and see what it's reading.

[jcbjs 260 0]

thanks for replying to my query, it is a very annoying problem. will try the injectors next. thanks again

[ESPREE 2]

I know this is an old thread, but it appears that a few others have had the same hot start issue that I have now. Anyone resolved this or have more info on what did or did not work? The thread just ends with no definitive answer.....

[ESPREE 2]

Ok, I heard from one of the original posters that the new injectors did indeed solve the issue for them. One of theirs was leaking. So I will try out the full throttle test and see how it goes. Thanks everyone!

[ESPREE 2]

Just an update... Tried the full throttle test but it made no difference. I know that my throttle goes to 100%, but I may not have been doing it right either. Had to let it cool down for a bit and then feather the throttle to get it started (then it ran fine).

Are there any other tests to determine if an injector is leaky without taking things apart? Are they easy to replace? Thanks for any info.

[WEllison 9]

The primary injectors are under the plenum, and are a pain to get to. The wiring under the plenum is difficult to unplug, you need a small mirror to locate where they plug into. I have used custom made wooden spacers under each end of the plenum to space it up while I fish around for the plugs. Once the plenum is removed the injectors are very easy to replace. Just lube the o-rings and pay close attenition to seating the injectors, it's a long way back in if they leak becuase the o-rings are damaged or not seated.

I like RC Engineering disc injectors.

I know of no EASY way to test for leaking injectors in place. You could try pulling the injectors fuse and crank the engine with the throttle WOT for 10-20 seconds when the engine is hot to see if it clears "a flodded condition", put the fuse back in. This is just another way to try Mike's suggestion above.

[ESPREE 2]

Hi Wayne,

Thank you very much for the info. Secondary seals would be easier though?

[WEllison 9]

Secondarys are very easy, access is right on the end of the plenum. See Marcus's response above, just loosen the clamping bracket. Careful with the o-rings as always.

[ESPREE 2]

Thanks again. I'll post with the results.

[Günter 28]

Kent:

feed & return for the fuel is on the RH fuel-rail & LH pressure regulator

..as so you could undo the pipes and pressurize the rails with fuel externally, if you add a fuel-pressure manometer on the shrader-valve port you could measure pressuredrop per time. To determine is it primary or secondary jinjectors ust manufacture your own 'bridging' pipe to override the two additional [secondary] plenum injectors (the quickfit connectors are of the 9.8mm type -so the bigger one available in open market).

If you still have a pressure drop it must be on one or both of the rail feeds [injectors Nb. 1-8], if not one or both of the plenum injectors caused the pressure drop -if both systems are OK, check the pressure-regulator on LH fuel-rail (that's the fuel return way) ..or maybe the fuel pumps itself for basic pressure delivery

[ESPREE 2]

Hi Gunter,

Thanks for the info. He did put in new secondary injector seals this week but no change. Waiting on a temp sensor now to see if that helps, then onto fuel maybe as you have described.

It occurred to me that I had a similar hot-start issue in the past with a different vehicle (1982 Chevy Blazer). It would start up fine but then once warm it wouldn't restart for anything (until it cooled down anyway). Usually the battery just gave out trying.

In that case it was electrical - once we replaced the entire distributor assembly the problem went away.

On my Esprit I know that the "coil packs" are new (changed at the rebuild), but does the Esprit in general have a distributor like my older Blazer or is it something different? (pardon my ignorance!)

I'm wondering if there is a simple spark test to see if it might be on the electrical side. Can you just pull a spark plug wire and hold it to ground to test?

Edited April 26, 2012 by ESPREE

[Günter 28]

it is not good to work 'without focus' ..so why this: "he put on new secondary injector seals.." -have they leaked ??

First step is to check and simulate all situations, this way you should see a weak point much easier

the ignition system is seperated into two coil-blocks, just like two 'four pot engines' in one engine block (what it realy is, from the constructive point of view) ..and the ECM powers up in a 'wasted spark' arrangement per full turn for every two cylinders of each bank.

If you want to check for ignition: -you can unplug the cables one after the other from the sparkplugs (undo the small curved sparkplug-covers) while the engine is running (undo and refit one after the other) .

If you listen to the change in sound of the running/firing charateristic you can find if a cylinder is not working.

As said -if there is no difference if you unplug a wire end, an place it insulated somewhere else, the related cylinder was not firing at all. If the engine tries to stall or rumble -the cylinder was firing fine.

If you find a cylinder who is not firing under your cold/hot conditions -undo the sparkplug from the head, place it on the ignition cable and 'ground' the sparkplug onto the engine block. If you see no spark change for an other sparkplug, ground it and watch again... or other way: place a small nail into the cable head to simulate a sparkplug ..and hold it near to the engine block -this way you should see if there is a spark going along from the coil to the cable end. If there is no spark, but one on the related cables of the same head (mention LH coil is powering RH cylinders and vice versa!) -go there to unplug the cable on the still fitted coil pack and add a 'flying wire' (strong insulated of corse!) from the related coil port to the block and hold it near to 'engine ground' to simulate the normal condition. If you see a spark the coil is powering and the sparkplug cable was just not working, if there is no spark the coil does have a fault under your running conditions

You cann get acces to most of the sparkplug-cables on the coil with the plenum fitted (aka engine 'running') -but you would need a plier with long ends

Edited May 2, 2012 by Günter

[Ozzy 0]

Just read your problem I did have the same fault when I first bought mine, but found when hot the cam sensor gave incorrect signal causing perlonged cranking but if persisted would eventualy start, it only uses signal for start, once running you can disconect and engine will run fine until you turn off and try to restart

Now after changing sensor perfect every time hot or cold, this part is not expensive and is very easy to change it is situated on the right hand bank (O/S) at the rear of the cylinder head.

Good luck hope this helps

[ESPREE 2]

Hi Gunter,

Thanks for the detailed info. We replaced the secondary injector seals because someone had suggested it, and they were only a few dollars. They were actually leaking a bit (on the outside) when the rebuild was done because some of the powder coat had gotten into the threads, so it seemed like a good place to start.

I have a feeling it might be the crank position sensor (I hope it can be that easy!), but I agree that it makes sense to be logical about the troubleshooting to narrow it down. Thanks for the tips.

Just read your problem I did have the same fault when I first bought mine, but found when hot the cam sensor gave incorrect signal causing perlonged cranking but if persisted would eventualy start, it only uses signal for start, once running you can disconect and engine will run fine until you turn off and try to restart

Now after changing sensor perfect every time hot or cold, this part is not expensive and is very easy to change it is situated on the right hand bank (O/S) at the rear of the cylinder head.

Hi Ozzy,

Thanks for the info on your similar experience. Is the "cam sensor" the same as a "crank position sensor"? I have found a few other posts that have indicated this might be it.

Edited May 2, 2012 by ESPREE