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Lacking a lot of power for some reason?


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Hoping someone can help resolve what I hope will be a simple fix? Yeah I know it’s a lotus I’ve had four of them now and it’s rarely simple. OK, I have a 2001 V8 with only 18600 miles on it. It’s been off the road for 14 years while living overseas and while I did some work on it. Now it’s up and running it’s as slow as a dog. My wife’s M140 absolutely thrashes it! My X6 diesel is probably quicker! So, in the process of having the engine out to make life easier to work on the damn thing, I’ve replaced the timing belts using the correct timing tools, the waste gate actuators have been replaced as they were seized, I have hi pass cats fitted and a stainless steel sports exhaust now. I have also blocked off the EGR for now due to the blow off valves I’ve fitted getting in the way After a few issues getting it running with a misfire due to two HT leads being round the wrong way and the same with the O2 sensors, it’s starts ok, but the idle is a bit lumpy at times. I’m not getting any error codes for the EGR, but it does throw up P038 which is the knock sensor on bank one. But the car just does not pull like it should. I can hear the blow off valves venting so I know I’m getting some boost while driving the car, but it’s just flat above 2-3000 rpm when it should be pulling really hard above 3000rpm. No other fault codes so I am at a bit of a loss. The way it accelerates feels like there is just no boost. Any help would be greatly appreciated thanks 🙏 

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Hey Freddie,

Sounds like a fuel delivery problem. Easiest one to check is the fuel filter.

With the car sitting for long the fuel probably has some water in the tank and that could completely block your delivery because the filter is full of water. 

Second, fuel pump.

Also I have seen a dirty air filter dramatically reduce power.

2 choices, fuel or electric unless something is broken in the engine.

 

atb,

Richard

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Based on the symptoms I would start with checking of blocked cats or lack of fuel pressure.... but you have new high flow cats, so you could discount that one.

Check the fuel pressure and report back.

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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14 hours ago, Elite 4.9 said:

Hey Freddie,

Sounds like a fuel delivery problem. Easiest one to check is the fuel filter.

With the car sitting for long the fuel probably has some water in the tank and that could completely block your delivery because the filter is full of water. 

Second, fuel pump.

Also I have seen a dirty air filter dramatically reduce power.

2 choices, fuel or electric unless something is broken in the engine.

 

atb,

Richard

Hi Richard,

I replaced the fuel pump a while back while trying to get the engine started as both pumps were dead. New air filters, but I will check and replace the fuel filter as it’s relatively cheap and easy to do. There was a bit of old fuel in the tank which should have purged by now as I’ve run the car a fair bit and topped up with fresh fuel.

I will keep you posted.

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7 hours ago, mike_sekinger said:

Based on the symptoms I would start with checking of blocked cats or lack of fuel pressure.... but you have new high flow cats, so you could discount that one.

Check the fuel pressure and report back.

Hi Mike,

I’ve had my laptop plugged in and not showing any low pressure fuel codes. I get a P0328 which is a knock from bank one. I get this consistently at the same rpm, manifold pressure and temperature etc. I’m not sure what’s causing the knock? 
 

I saw a post regarding a similar problem and one of the test was to disconnect the pipes to the waste gate actuators to find out if the boost solenoid is doing it’s job properly? The car should run like it’s on steroids without the actuators relieving the overboost. While I cautiously tried this there was a slight improvement, but I was reluctant try any excessive throttle opening with fear of over boosting the engine and causing some damage, but even at about half throttle the engine is still pretty lame. The blow off valves were dumping the pressure on gear changes so I’m bit flumaxed why I’m lacking performance, other than a significant air leak which I’d then expect the blow off valves not to be so vocal?
 

If there is an air leak would I not get a code for a lean mixture? I’m wondering if this is what is causing the knock? While I haven’t driven the car for over 14 years I had an M5 and drive my wife’s M140, so I know what the pull should feel like and it’s just not there. Once gain any     advice I’m thankful for and willing to explore to get eh car running as it should. 

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There are no low fuel pressure codes, you need to get a pressure guage on the right hand fuel rail.

279322871_1339677689859553_6517389783160177840_n.jpg.ac5659184acff53a70edbd65c3a465dc.jpg

If you can establish that the static fuel pressure is correct, then I would be checking that the fuel pressure regulator has a good plenum source.  It could be that you are not seeing the rising rate in pressure due to that not being good.  Perhaps that was not connected securely when you did you blocked the EGR?

279437306_1157714931696694_1065713668863468142_n.jpg.662c19b0a2cb7a77fe5bb2a8d0662fc6.jpg

Don`t forget to reconnect your wastegates in order to ensure boost control.

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1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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20 hours ago, mike_sekinger said:

There are no low fuel pressure codes, you need to get a pressure guage on the right hand fuel rail.

279322871_1339677689859553_6517389783160177840_n.jpg.ac5659184acff53a70edbd65c3a465dc.jpg

If you can establish that the static fuel pressure is correct, then I would be checking that the fuel pressure regulator has a good plenum source.  It could be that you are not seeing the rising rate in pressure due to that not being good.  Perhaps that was not connected securely when you did you blocked the EGR?

279437306_1157714931696694_1065713668863468142_n.jpg.662c19b0a2cb7a77fe5bb2a8d0662fc6.jpg

Don`t forget to reconnect your wastegates in order to ensure boost control.

Thanks Mike,

I will take a look at the weekend as working away during the week. Will double check the connection for the fuel pressure regular too as I know how easy it is to miss things at times.

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  • 2 weeks later...
On 03/05/2022 at 12:58, freddielacey said:

Thanks Mike,

I will take a look at the weekend as working away during the week. Will double check the connection for the fuel pressure regular too as I know how easy it is to miss things at times.

OK, so I connected a pressure guage to the fuel rail and I’m only getting just over 40psi when I turn the ignition key on and then the pressure drops off pretty much instantly. As soon as I start the car though I’m getting 40’ish psi at the fuel rail. I’m guessing this is lower than it should be? (I need to check the accuracy of the gauge later, but I’m sure it’s going to be within a few psi as it was relatively cheap off Amazon) I replaced the pumps in the tank last year as they had packed in, so my question for now is what should I be getting fuel pressure wise and should the fuel rail be holding that pressure and not dropping off? Then I need to find the cause of the low fuel delivery pressure. Any clues or tips would be greatly appreciated. I’m hoping this is the cause of lack of performance and why I’m getting a knock fault code at around 4000rpm, which I’m assuming is due to the engine being too lean? First off I’ve got to fix my sons mini though 😞

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Your static fuel pressure should be close to 45-50psi and should not drop-off completely immediately after the priming of the rail.  If you have a cheap gauge, it could be that your 40-ish is actually enough in terms of static pressure.

Did you check your plenum source to the fuel pressure regulator?  As mentioned before, it could be the case that if your plenum source is not firmly connected, you are not seeing the rising rate in pressure as your boost builds.

 

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Hi Mike,

Yes, the vacuum tube to the fuel regulator seems sound. I’m guessing part of the issue is there is a leak somewhere which is why I’m seeing the fuel rail pressure drop off literally within a couple of seconds, although it maintains pressure when running, occasionally dropping a few psi when blipping the throttle. 
Not sure if these indications are related or not, but when I plug my laptop in and use the OBDI diagnostic lotus V8 tool, I can switch the primary fuel pump on and the pressure jumps to just over 40psi and holds for while the pump primes for 3 seconds then drops off. If I turn on the secondary pump, I can hear the relay activate but the pump doesn’t. Not sure if this also needs to be enabled by a speed of 130mph or not. Also I’m not really seeing any TPS % when opening the throttle, occasionally I get 7-8% showing, but would have expected this to be responsive and progressive when throttling the engine.

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Your comment regarding the TPS is important.   You should be able to observe a solid TPS reading from 0-through to 100% and all value between.   If you cannot observe a reliable and progressive reading, the it would a candidate for replacement.

Check first that the connections are clean and free of any corrosion. Corrosion can of course affect the resistance and readings.   If all looks good and you are still not observing a reliable reading over OBDII, then I would replace the TPS.

 

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1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Already checked the connections as used to be an avionics technician, so know how important this can be. Do you know if the TPS % value will read on the OBDII without the engine running so I can get some indication to test it? Will get it removed in a bit and see if I can get any measurements out of it on my multimeter. 

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You should be able to see the TPS reading with the ignition on pos II.

It is important that it goes all was to 100%.  There is an adjustment on the pedal just in case you need to increase the available travel.

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Ok, I’ve had the TPS sensor off, tested it and it works fine. I think the lack of reading is some latency with my laptop and bloody MS windows! Check one problem to find another though. Now I can’t get the sensor back to zero. Furthermore, I am not getting 100% throttle movement from the peddle. I know there are some issues with the accelerator peddle catching in carpet etc, so will sort this before proceeding further.

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Ok.  Make sure that the bellcrank of the throttle is also free of any obstructions and can travel freely through its full movement.

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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I am going to adjust the throttle linkage tomorrow as it’s not set correctly at the moment. I believe  you can get the ECU to relearn the idle position as there is no adjustment in the sensor itself and currently at idle it is reading 8%.

Looking at my workshop manual it’s stating a minimum of 55psi fuel pressure on priming and this should only drop by about 6-12psi once the pump stops running. I’m getting at best 42psi and losing pressure straight away (within a second or two), so I am wondering if the fuel regulator is just dumping the pressure straight back into the tank? There is a test to check the regulator builds pressure, which I’m assuming closes the regulator feed back to the tank based on plenum pressure. My logic is that as plenum pressure increases, it closes the valve to increase fuel pressure to keep up with increased in air volume? I will try test the regulator tomorrow and let you know where I am from there?

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You can reset your IAC once your adjustments have been made to the throttle and you are seeing 0% TPS at rest.  The procedure for IAC reset relies on being able to depress the throttle to 100% multiple times within in a short period, so that needs to be fixed first.

Reset procedure:

- Ignition to pos II

- Depress throttle to 100% 4x (holding for 2 seconds each) within 20 second period

- Leave ignition in pos II for 60 seconds

You are right about the Pressure Regulator.  The pressure signal from the plenum acts together with the spring to effectively increase the rail pressure as boost rises.

If your regulator is defective, then that`s another candidate to be replaced....

280266228_523016675966395_5797658357027563202_n.jpg.6b18b9ae3a80ea53777cce1af8f9945b.jpg

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1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Finally, some progress although not there yet!

I managed to reset the TPS sensor as you suggested and that now reads correctly. There is a clip missing from the throttle cable which I will try order tomorrow so I can adjust the cable and peddle movement correctly, but expecting it to no longer be available 😞

I disconnected the fuel return feed post the fuel regulator to see if it was functioning: no fuel being returned to the tank so this eliminated the regulator being stuck open, for now! Still not enough pressure in the rail to see if it functions correctly.

I replaced the fuel filter and got slightly slower fuel pressure decay, but still barely 40psi (see video if it attached), so I’ve had to do what I was dreading……out with the fuel pumps. Not so bad getting them out as I’ve done it before, just getting everything back in, you need  triple jointed 8 foot long arms to reach in around and I already have an 8mm socket lost in the depths of the car from last time 😡 
 

I found a split on the fuel hose above the secondary pump. Removed it and blew down it with the end blocked and it appeared to be airtight! So, I made up a quick fuel rig to test the pumps and the fuel hose. As expected under extreme pressure the split hose leaked everywhere. Fortunately I have some spare from when I replaced the pumps last year. Annoyingly when testing the pumps the secondary pump has failed 😣 The pick up filters didn’t look great so I will purge the tanks and rinse them out with fuel to try remove any remaining silt from some corrosion in there. The primary pump is good and was producing over 100psi of pressure. (My gauge only goes to 100psi.)

I will order a new pump tomorrow and get this fitted in a week or so when I have some free time to tinker again. I will keep you posted.

Need to get showered and changed now as wife doesn’t like the “odour de 95RON”  😂 

 

0E75C699-57AD-4417-A841-8AABDCA86375.jpeg

9EC3D354-9B84-468F-86B0-D01C8949281F.jpeg

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Good to see you are getting there.   Looking forward to the "we have warp speed"  post next week 🙂

 

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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