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No accelaration or power

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No accelaration or power
#1
  This topic is about my 1980 Triumph TR7
Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hey guys,

I've been working on my 1980 TR7 FI project car for about a year now. It had set for many years before I purchased it. I've replaced the complete brake system and complete fuel system (injectors, lines, tank, regulator, filter) removed and completely cleaned plenum chamber. I replace timing chain and the chain tensioner (the crankshaft pulley timing mark, camshaft line and the Jackshaft line are all correct) it was rattling and making noise.

The engine will start and idle ok (not perfect). But as soon as I try to accelerate (increase RPMs) it spits and sputters and then dies.

Any ideas what I need to try next? I am stumped.

You guys have been very helpful in passed I am hope for some good advise to solve this issue.

I appreciate any suggestion and advise.

Thank you,

GarryB

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sbs Avatar
sbs Steve S
Previously you reported "Good power and acceleration on flats, but nothing on hills."

It's gotten worse?

What did you change in the meanwhile?

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Steve,
The girl had power on flat road but “no power on hills”. As stated in last message.
The timing chain has always made a loud rattle. So, I replaced the timing chain and tensioner. I changed the Fuel Regulator and removed and cleaned the plenum chamber (thinking it might be clogged with dried ethanol, like the tank was).
I’ve included picture of the crankshaft and camshaft marks and the rotor. They are set as per the manual.
Thanks,
GarryB

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR7 Drophead "The Great Pumpkin"
1980 Triumph TR8 "Wedgie"
Garry:

Sounds like your MAF sensor might be giving you fits. The FI computer looks at the MAF sensor to determine how much fuel to add.

Is it sticking or worn out? If it is worn out, there are services that will rebuild them if you cannot scrounge a good one. The TR8 MAF is unobtanium, for example so when it goes bye-bye, you need to have it rebuilt.

Vance



1980 Platinum Metallic TR8, frame off restoration, complete.
1980 Vermilion TR7 Sprint replica, in progress.

darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
I realize you replaces a lot of the FI system, but I would start there. I was trying to find a web page that I had before that when through a very thorough debugging of the Bosch L-Jetronic system, but I can't find it. I was a Fiat or Alfa page I think, but the system and concepts are all the same. You should test things like the temp sender, AFM, and fuel pressure.

Found the link:

http://www.hiperformancestore.com/ljetspider.htm



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA



Edited 1 time(s). Last edit at 2018-10-25 07:45 PM by darrellwalker.

Andrew1966 Andrew Ward
Abbotsford, BC, Canada   CAN
Many problems in fuel injection can be traced back to a bad ecu.

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hey Vance,

Thanks for your input. I found a YouTube on how to clean a MAF. Think I will start there. If, it needs to be rebuilt do you have any sources for that?

As always, your help is greatly appreciated,

GarryB

mcmahontr7 Chris McMahon
Fort Worth, TX, USA   USA
I’ve been there and done that on the FI TR7! They are touchy. Have you timed it using a timing light yet. The touchy part is making sure you get the idle, timing mark and air/fuel ratio screw right on. Play with the distributor. Mine is 8°btdc while idling at about 1000-1200 rpms.

How are the plugs, wires, cap, rotor and coil? Don’t forget that the firing order is 1342. It’ll still run at 180° off, but bad.

Doublecheck the all the hoses. Especially the large hose from the air filter to the throttle body. And the hoses to the auxiliary air valve.

I have tested and cleaned my Air Flow Meter. (AFM) I also adjusted the spring and and arm that is on the potentiometer track inside. But I wouldn’t mess with the AFM without making sure the dynamic timing is right on. Your static timing is right on.
I wish I were there,

Chris

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Vance,

Thanks for the guidance and suggestion.

I have disassembled the air intake and to the Air Flow Sensor (pictured below).

If, I hold the flap slightly open (with vise grips) the engine will idle and run fairly good, it will also accelerate ok. When I throttle it up the flap in the AFS does open wider on it's own.

If, I try to start it with the flapper closed (no vise grips) on its own, she will not run.

Any idea what would cause this scenario?

I appreciate and help and or suggestions.

Thanks,

GarryB


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Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Darrell,

Thanks for the suggestion.

I will be trying to follow Greg's "Step by Step" Fuel Injection check and adjustments.

Seems to be very thorough and a complete check list.

Appreciate your help,

GarryB

darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Garry,

The flap also controls the fuel pump. I would have to double-check if the pump is also powered during cranking from another source (I think it is), but if you need to hold the flap open to get the car to idle, that could be the problem. The question then is why isn't it opening at idle? It is pretty sensitive, so either you have a vacuum leak, or the flap is sticking. It should move with virtually no pressure.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hey Chris,

Thanks for your suggestion.

I have checked all hoses and clamps.

New plugs, wires, cap and rotor. I've replaced the module on the bottom of the coil, seems to have good output now.

I will be rechecking the vacuum hoses over the weekend.

Thanks for your help,

GarryB

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR7 Drophead "The Great Pumpkin"
1980 Triumph TR8 "Wedgie"
In reply to # 1574215 by Lagodude Hi Vance,

Thanks for the guidance and suggestion.

I have disassembled the air intake and to the Air Flow Sensor (pictured below).

If, I hold the flap slightly open (with vise grips) the engine will idle and run fairly good, it will also accelerate ok. When I throttle it up the flap in the AFS does open wider on it's own.

If, I try to start it with the flapper closed (no vise grips) on its own, she will not run.

Any idea what would cause this scenario?

I appreciate and help and or suggestions.

Thanks,

GarryB

The fuel pump is controlled by the ECU. The ECU will not command the pump to run unless it 'sees' the air flap move such that there is air flowing into the engine. This is a safety feature so that if the car is in an accident and the fuel system is damaged, the pump will shut off when the engine stalls rather than (potentially) pumping fuel all over the ground and creating a fire hazard.

If you need to hold the MAF air flap open to get the car to start, then there is likely something wrong with it. The flap should open slightly on its own the instant the engine begins to crank. A common failure of the MAF is that the position sensor for the flap simply wears out, so the ECU cannot see the flap open. In this case, you need to replace or rebuild the MAF. Rebuilding services are available should you be unable to locate a good replacement. The TR8 MAF is simply unobtainable and must be rebuilt. My understanding is that the TR7 MAF is a straight up Bosch unit, and replacements are available.

Vance



1980 Platinum Metallic TR8, frame off restoration, complete.
1980 Vermilion TR7 Sprint replica, in progress.

MAGILL Mike G
Klamath Falls, OR, USA   USA
Hi Garry, our local library has a 1980 Motors Import Repair Manual in the reference section that seemed to have some pretty good diagnostic sections. Also the Wedge Owners have a diagnostic tool available to members called the "Gizmo" that, as I understand it plugs into the diagnostic port under the glove box and helps with idle adjustment and general diagnostics. A good reason to join the Wedge Owners.

Mike Gillette
1980 TR7 Spider

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi guys,
Back to the same issue. I have replaced all vacuum hoses. Still the same problem. Anybody have answer to what the pictured chamber in vacuum system is for? It’s mounted on the on head and bolts to intake manifold. Used smoke machine, no leaks now. Any ideas of what we to try next.
Help is greatly appreciated.
Thanks,
GarryB


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