drivability problems

[SENNA01]

i have a 1989 esprit turbo gmp4 fuel injected car,i,ve had a problem which i thought was cured but is not.when the car is warmed up driving on the highway at about 3000 rpm i give it gas and it stumbles all over itself won't take throttle.i checked the timing put a new fuel filter on checked all of the vacuam lines,etc,could it be the wastegate capsule diapram broken or the turbo,also my fuel pumps are very loud could they be weak,any help from anyone on the forum with knowldge of my problem would be greatly appreciated,i live about 1500,miles from my nearest dealer so any help would be great,i just don't want to spend megabucks chasing deadends,thanks btw great forum

[Del-Esprit]

The stumble around or below 3k is unfortunately a known issue on esprits, not sure why and despite attempts by many not easily curable if at all. Best bet if you have and ECU it is possible to get the stumble reduced and pickup improved by changing the standard chip for an improved version as available from P.U.K. Racing or Sanj, I believe they are both the same ?.
Can't remeber if your car has an ECU that is modifieable or not ?

[Lotusman]

I also have an '89 non-SE Esprit since 1996. Assuming you have no check engine lights, and Freescan didn't show any problems, then you must derive a solution from a combination of problems. Does it ALWAYS start moments after the starter starts? How is the A/C working?, etc. I thought I had a fuel pump problem when the car started cutting out. It turned out the ECM box was bad but I could keep the car running for another year by jumping out the pump relay before the timing in the box went out. Stupid I know as a replacement computer box costs only $80. Not the $600 like my Chrysler. Do you have the ECM and Shop manuals? I also live about 400 miles from the closest dealer so self-reliance and ability to have a Plan "B" is important when owning a Lotus otherwise it tends to stay in the garage alot. I had a Europa for 7 years with no dealers available, but having a shop manual.

After stumbling, does the car rev to 6000? With a check engine light on for the first 5 years of operation(Dealer check could't find anything wrong, Code 26) and with what turned out to be "limp home mode",indicated by the radiator fans coming on as soon as the ignition is turned on as explanation given me from the courtesy of Marcus(an indication I couldn't find in the manual), I could still get 120 mph out of it. Does the turbo gauge show increased boost pressure? Without an upgrade chip you can't expect more boost than the first line of the gauge, about .5 bar. I have heard the fuel pump will put out 3 or 4 times the needed fuel rate, and my dealer has so little call for new pumps that they didn't have one in stock.

I just put the No.15 chip in my non-SE and I think it has quieted the engine. I took the muffler off earlier and my audiometer does'nt lie, 80dB at 10 feet away.

So to get help here we need more info. And as the other post says, maybe you have no new problem.

Lotusman
'89 non-SE

[Red_Devil]

Beside 3K syndrome, my S4s once had same problem when CAT melted down and some part stuck at EBPV, make it cannot fully open, exhaust gas can't free flow then rev is stucked. If your 1989 has EBPV, just disassamble, if anything stucked inside just take out. Worth to try. Wish this may help.

[SENNA01]

thanks for the replies so far,its not the usual 3k stumble there is no throttle response whatsoever,but when i start the car again its fine for short period of time,the car does have an exhaust valve checked it and its functioning properly,its almost like a throttle position sensor??? the reason i think it could be the fuel pump is that it has been very noisy for a while,maybe its just not pumping sufficient fuel now? by the way is the ecm really 80$? where could i get one will a gm ecm interchange? thanks for your help

[cnh1990]

My SE made that sort of symptoms when the spark plugs were burnt. They only last a max of about 10-12K depending on how you drive. The turbo cooks them. NGK are aout the best. Champions the worst only 2-3K and they are burnt. When the plugs are burnt (electrode edges round) you stomp on the gas and it sputters and stumbles like it went into over boost protection. It runs weird because the unburnt gases via the 02 sensor make the engine think it running rich and then it tries to lean out mix. I suppose that is why it feels like it is running out gas.

Calvin

[SENNA01]

calvin the plugs are ngk and i just checked them,they are fine i only put them in 2000 miles ago,thanks any other suggestions??

[sanj]

SENNA01 said:

i have a 1989 esprit turbo gmp4 fuel injected car,i,ve had a problem which i thought was cured but is not.when the car is warmed up driving on the highway at about 3000 rpm i give it gas and it stumbles all over itself won't take throttle. also my fuel pumps are very loud could they be weak.

Your fuel pump shouldn't be loud, you should just barely be able to hear it for two seconds if you turn the key to the 'on' position without starting the car. There is a pressure test port on the end of the fuel rail, any GM mechanic should be able to test the pressure, which should be in the 30-55psi range, depending on vacuum/boost conditions.

Cheers, Sanj

[SENNA01]

thanks sanj,i will get the pressure checked,the fuel pump sounds like a cow in distress,i really think this could be my problem will let you know,thank you!

[SENNA01]

i just wanted people to know that the fuel problem i was having with my 89 mpfi esprit was the fuel pump and that it is exactly the same as a 86 sunbird turbo fuel pump.i installed it in the car and it is working better then ever,hope this helps someone in the future