Hot Start Issue

[pete2528ca]

Hey gang.

New guy here (not new to Land Rover, have had mine for 5 years)

Here is the issue. When cold the engine starts fine. As it comes to operating temperature, say after I have gone to the store and then come back to start it up after about 10 minutes or so, it sputters revs are very low and it stalls. I try again and it does the same thing. If I am luck and the revs stay at say 200rpm and I hit the gas pedal and keep it at about 2000rpm it is ok enough to get going and then it drives fine.

After it cools down for about 20 minutes it starts ok again.

It is a 1997 Discovery. non advanced emissions family. 170K km on the clock.

I have changed the following within the last three months:

New NGK ignition wires.
New Champion plugs
New Coolant Temperature sensor
New O2 sensors post catalytic convertor
Relitively new O2 sensors pre cat.
New gas cap
New Thermostat and gasket
New Coolant
New Battery
New Oil
New Air Filter.

Cleaned the MAF
Cleaned the Stepper motor
Cleaned the Throttle position sensor

I don't know where else to look. I have on order the following parts:

Fuel temperature sensor (for in the fuel rail)
New Fuel Filter
New hoses for the PCV system
The little oil separator that goes in the left hand valve cover.

Apart from that I am lost. It starts relitively fine. There is spark and Fuel. The only codes it ever threw were for the O2 sensors.

I have read that the fuel temperature sensor can cause hot start issues.

Any help would be greatly appreciated.

Thanks all.

[dandruka]

Hey

My 99 DI did the same thing. Do you smell gas in you exhaust too?

Anyway, I looked at all the stuff you did with no luck until I addressed the fuel injectors.

I guess they were leaky...caused a rich start which translates into poor starting when hot or warmed up.

I actually replaced them becasue they were beyond the over the counter meds!

[Joey4420]

Agree injectors, or worse case the fuel pump is telling you it is time to shop for a new one.

[pete2528ca]

Thanks guys.

I think since I have the fuel temp sensor coming I'll swap that out and hope for the best.

If need be then I will change the injectors.

ARGH!!

[Dashface]

Would injector problems also be causing the truck to stutter at highways speeds sometimes? Because I get that too.

...If so, I guess I'm getting new injectors ha ha.

[Rock]

I am having the same problem, have you fixed yours?
Jesse

[flightdawg]

Thank god someone understands my pain! I've been fighting this problem for months. Down to replacing the fuel regulator or injectors. I'll wait to see what happens.

[dandruka]

Hey dashface,

I think you need to replace your potentiometer AKA throttle position sensor. Seriously…

It’s a minor part on your plenum/air intake…however, the damn thing will cause your engine to rumble periodically…often time as you let off on the throttle as you would on the highway or just cresting hills

Below is an excerpt from Land Rover Fa-Q

From: Stuart Williams (STUARTW@po1.net.cho.ge.com)
To: Land-Rover-Owner@uk.stratus.com
Date: Mon, 27 Nov 95 08:11:00 EST
Subject: Disco Throttle Problem - FAQ Candidate!
I recently developed a problem with my '95 Disco (the first real problem in 14K miles) that required dealer intervention. The problem was a brief engine stumble or cutout whenever the throttle was eased after cresting gentle hills or when running on flat terrain at 70 MPH or so. It happened with or without the cruise control operating, and with or without the OD engaged. The engine would immediately resume normal operation, but the vehicle would lurch noticeably as everything caught back up with itself. Duncan Brown tells me that this is normal behavior for his 1960 Series IIa, but I was not thrilled with it happening to my Disco given the upcoming holiday weekend and some planned travels around the mid-Atlantic. At first I thought that it might have been transmission slippage or OD problems but the RPMs would actually visibly drop on the tachometer during the infrequent longer incidents, so I had visions of new Engine Control Computers and other Lucas bits dancing in my head. The dealer's first suspicion was the fuel pump, so they set up a pressure gauge and took the vehicle on the road but could never see any drops in pressure during the fairly easy to duplicate stumbles. Next they attached a diagnostic monitor to the ECC and sent two technicians on the road, one driving and one riding shotgun on the monitor, to see what they could see. Sure enough, the signal from the TPS (Throttle Position Sensor, Roverese for potentiometer) was intermittent under certain conditions and was momentarily sending signals to the ECC that caused the engine to fall back to idle, albeit briefly. They say that this sort of thing should have caused the 'Check Engine' light to come on, and it probably was, but things corrected themselves so fast that the dashboard light was never observed. Maybe a latching circuit would be helpful here, although that might be a double-edged sword given everything that's wired to that indicator! Anyway, they replaced the TPS under warranty and we're back on the road, better than ever. Kudos to Drew, the technician at Land Rover Richmond that found the problem.
For the life of me I can't imagine why the Throttle Position Sensor might have worn out !!!
FYI

[petedisco]

did the fuel temp sender fix the problem?