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Only 124bhp at the wheels. Ouch!!


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I got a disappointing result at the SE meet at Surrey Rolling Road last week. Only 124bhp at the rear wheels. I've had the car 1yr bought from importer with little or no history. It's a 1995 2+2 NA Auto (probably all the wrong combinations for performance). I was told that the cam belt was changed at around 90,000 kms and there is an aluminium plate in the engine bay that says so in Japanese (I think that's what it says!). Its now done 80,000miles.

 

However, because I've not anything to compare it to, the fastest thing I've driven to date was the old 2.8i Supra, I'm not aware of any power loss. Any sluggishness I've put down to the auto box. It is pretty slow off the mark but if you kick down and it finds a lower gear it seems to take off ok. Mid range acceleration in kick down seems ok too, although the other week I was left for dead by a new TVR Griffith. The engine note is fine and smooth, there don't seem to be any added noises, there's no smoke from the back and no oil on my driveway.

 

The boys at Surrey RR were mumbling something about running rich and air flow meters etc so I've booked it in at MJPautos nr Chelmsford this weekend to be sorted out.

 

Any of you guys anticipate what they'll find?

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damn, sorry to hear that mate. whats the power at the fly then...180 tops? you are right about the wrong combination though, but you didnt buy the car for its performance, did you? personally i think looks and ride quality are more important in a NA LWB.

 

im not an authority in any way on autos, but there is always an order of things to check when looking for lost power:( did you book the car in with MJP eastern auto (brentwood- mikey boy feeney) or are they completely different? ) find someone with a conzult! (mike has one). find out if all your electronics are functioning properly to start with- the trouble with old cars, looms get hot on a v6, connectors get brittle and crack...etc.

 

then its all down to the engine and trans. compression test, gasket replacements, flush oil lines and fuel lines, see whats going on in there to clog up the power.

 

hope this helps.

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...clogged air filters. If you want, I've a 95na manual and a 97 na manual that you can try. I'm in Ipswich. I had a 91 na auto before these two, and yes the drives different, but not that different. The 97 na's been dynoed at 200bhp at the wheels.

 

Good luck

 

Jack

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Guest andyduff

Was gonna suggest exactly the same Paul! Also, check the base timing. Really need a consult for this though so you can see what timing the ECU thinks it is running.

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Thanks for all the comments lads. Answers as follows;

 

Yep, I bought it for it's looks and general street credibility. I've a 14yr old son who loves it although a Skyline might impress him more. I'm getting a bit long in the tooth and not up to too much modding so a nice gentle smooth ride is what I'm after, with good looks and some urgency. I cant afford a DB9.

 

The RR bloke said about 175 at the fly max.

 

Yes it's the same MJP auto (there can't be 2 MJPautos in Essex both specialising in Nissans and Zeds, surely?). I got the address from this web site and they come highly recommended and yes they do have a conzult.

 

By the way that TVR was moving I expect it would thrash most cars on the road today.

 

Thanks Jack for the offer of a drive. I'm looking forward to driving my car with it's expected dose of horsepower ie 220 at the fly. That may come as a pleasant surprise as I've been tootling around on only 175!! I may hold you to the offer. 200 at the wheels for an NA sounds good.

 

Someone at the RR did also mention that putting the calm belt on one tooth out does make a difference to output. We'll have to see what MJPauto come up with.

 

By the way, in addition to having a low power output the old girl was lacking in torque too.

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Andy

 

...when the problem's sorted, let us know what was done. Always usefull to know for future reference.

 

Good luck

 

Jack

 

Ok. Got the car back last night from MJP Eastern Auto and it's created quite a puzzle. they used ConZult to do most of the diagnostics and this is what they came up with:

 

1. Vacuum leaks - none found.

2. Connector Corrosion - TPS, CAS, MAS, temp. sensor, injectors, coil packs - all clean, no corrosion.

3. Installation of timing belt - all correct.

4. Air Filters - some blockage due to dirt accumulation - replaced air filters.

5. Fuel filter - changed.

6. Check throttle bodies for carbon build up - some obstruction found. Cleaned with carb cleaner and freed throttle movement.

7. Added injector cleaner direct to new fuel filter and added remainder to tank.

8. Check fuel pressure and fuel pressure response - slightly low readings, but good responsiveness to throttle.

9. Check voltage to fuel pump and fuel pump operation - all normal.

10. Operation of PCV valves and system - all good.

11. Operation of air regulator valve and AAC system, clean - all good.

12. Check ECU for diagnostic codes - shows code for detonation sensor.

13. substitute ECU for earlier equivalent - improved driveability and responsiveness by comparison with the original 16 bit ECU.

14. Reassess sensors using ConZult via replacement ECU. All within correct parameters and behaving normally. NB ECU now shows fault code for Fuel Temperature Sensor as this unit is not present on later models!

 

 

So, basically MJP replaced 2x air filters (it looks like only one had been replaced at a recent local service. They probably didnt realise there were two!!), 1x fuel filter, cleaned the throttle bodies and swapped the ECU for a second-hand one off an earlier model.

 

I must admit it now runs much much better and the throttle response is amazing. However MJP reckon they haven't got completely to the bottom of things as they reckon power is still a bit short of the expected 210 at fly, but they have certainly corrected those horrible flat spots on the power curve.

 

I guess it's back to the Rolling Road!! Any more ideas from you guys??

Cheers.

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Code 34 - That will put car in safety mode, which retards timing and uses safety fuel maps. This will have a markable affect on performance.

 

Mike did suggest that he could replace detonation sensor but for the cost (£250 approx) he didn't think it was value for money in terms of bhp/£. Would you have it done? I'm planning to drive it around to get the hang of it again and if I'm still not happy Ill consider having it done too. If you think it's worthwhile I'll consider it more positively.

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Mike did suggest that he could replace detonation sensor but for the cost (£250 approx) he didn't think it was value for money in terms of bhp/£. Would you have it done? I'm planning to drive it around to get the hang of it again and if I'm still not happy Ill consider having it done too. If you think it's worthwhile I'll consider it more positively.

 

Bypass it...costs a few pence and takes only a few minutes.

 

The det sensor only works up to about 3000rpm anyway, and on an NA there is very little need for it in comparison to a TT.

 

You need to wire a 1megohn resistor into the det sensor connector.

 

details here : http://zhome.com/ZCMnL/PICS/detonationSensor/detonationSensor.html

 

I've seen TT's in safety mode producing over 100hp less than stock on the dyno....the affect wont be as dramatic on an NA...but it would account for your low power reading. The richer fuel maps and retarded timing its running in safety mode will also mean poorer mpg.

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Andy

 

Change the plugs - or at least check their condition. Use the platinum variants. Then chnge the oil in the auto box - MJP will sell you the right stuff - with a filter. After that it's weight reduction I'm afraid.

 

I would have thought that the later ECU (assuming it's standard) would be better for the car - 32 bit processor, thinks quicker.

 

Good luck

 

Jack

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  • 2 months later...
Andy

 

...when the problem's sorted, let us know what was done. Always usefull to know for future reference.

 

Good luck

 

Jack

 

This is to bring everyone up to date with this old thread.

I drove around with the 8bit ECU for a bit which did improve throttle response but there was still a massive hole or flat spot in the power curve. The car would perform ok for bits and then it would seem that the engine totally lost interest in pushing forward. It also became apparent that it had difficulty selecting the right gear appropriate for the speed and acceleration. I also noticed that the speedo would often "start" at 20mph.

I decided to have the detonation sensors fixed which didn't seem to make a lot of difference to the overall driving experience.

I agreed with Mike at MJP to recheck the Dyno afterwards and to compare the two ECU's; my original 16bit one and the 8bit that I had fitted. I'll try and attach the traces at the end of this note if I can work out how to do it. You'll see a massive dip in bhp around 4300rpm which then quickly recovers approaching 4600rpm.

It seemed that there was faulty wiring between the speedo and the gearbox (as evidenced by bodged soldering and loose wires etc at back of speedo) and a simple replacement of the speedo converter (SpeedM8 removed) seems to have done the trick.

Many thanks to Mike at MJP Eastern....now lets see if I can get these Dyno traces on here.... yours Andy

img002 img001

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