Diff Posted March 27, 2011 Share Posted March 27, 2011 I have a SLR which is being very special in the starting department. Story so far: 1. Cut out the FIA switch by going directly to the solenoid from the battery 2. Installed the relay modification 3. New Soleniod 4. New battery (Banner) 5. Cleaned the earth from the start to the battery 6. Battery voltage 12.85 dropping to 7v when cranking (slowly) Still cranking very slowly, not enough to start engine. When I jump it from the tin top the engine cranks fine and the car starts? I would be very grateful for any help! What have I have missed? Thanks, Ian Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 27, 2011 Share Posted March 27, 2011 If the battery is dropping to 7V when cranking ........ it is a sick battery ! Has it been fully charged and the liquids filled up ? Link to comment Share on other sites More sharing options...
Diff Posted March 27, 2011 Author Share Posted March 27, 2011 Thanks for the reply, The battery is new, filled up with Banner fill pack myself. Charged once (over 5 days) with a Optimate III. Ian Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 27, 2011 Share Posted March 27, 2011 Don't think an Optimate will provide enough grunt for a first charge from new ?? I think it is good for maintaining a charge. Can you charge it from a 'normal' charger, or start the car from the tin-top battery and take it for a 20-mile run to charge it up, then try a cold start the next day. Just re-read your OP ..... have you also removed and cleaned both ends of the earths (black leads), from battery -ve terminal to the engine and the one from the engine to the chassis ? The cable from the starter to the battery is the live +ve feed, not the earth ! Link to comment Share on other sites More sharing options...
Diff Posted March 27, 2011 Author Share Posted March 27, 2011 Hi, Take your point about charging with the optimate - will try the alternative method. I have an earth from one of the 3 starter fixing bolts to the -ve battery terminal. This, I have ensured, has clean terminals. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 27, 2011 Share Posted March 27, 2011 Have you also got earths from the engine block to the chassis (possibly an engine mount bolt ?) Link to comment Share on other sites More sharing options...
Diff Posted March 27, 2011 Author Share Posted March 27, 2011 Just got the strap from the engine to the engine mount off, looks as though it need a clean. Ian Link to comment Share on other sites More sharing options...
mattobrien Posted March 27, 2011 Share Posted March 27, 2011 Are your HT leads engaging properly with your spark plugs? I ask as mine was always a dog to start and one of the issues resolved during remap by the two Steve's was that the HT leads were not properly engaging. Steve fixed it by removing the casing around the plug end and pushing the wire further down. There was a definite click into place one it was engaged properly and it fired up like it had never fired up before. A potentially cheap and simple fix - possibly worth a look. Mine also fired easily when jumped - I guess the extra power helped the spark jump further. Good luck Matt Edited by - mattobrien on 27 Mar 2011 20:39:52 Link to comment Share on other sites More sharing options...
Ian B Posted March 27, 2011 Share Posted March 27, 2011 Shouldn't drop that low when cranking if battery and connections ok. Have you used the car quite a bit since installing the new and freshly charged banner? If so, is the alternator charging (do you get 14v+ with engine running?), or is the battery slowly discharging during use? Link to comment Share on other sites More sharing options...
Bob_Rich Posted March 27, 2011 Share Posted March 27, 2011 Hi Where did U measure the battery voltage? Was it directly at the battery terminals? if so then it does seem a bit low. if it was via any lead with starting current in it ( usually 200A+)it may be the drop in that lead. I have measured drops across leads and there terminals of up to 3V on starting in some dodgy cases. 7V at the battery could be a even lower at the ECU and it is just possible that the ECU may not respond correctly if the supply to it went too low. If possibly try a separate battery for the car and keep your existing one wired only into the starter then if it starts OK even with low cranking speed it might be the ECU dropping out. hope this helps best of luck Bob Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 27, 2011 Share Posted March 27, 2011 The ECU doesn't like anything much below 8-9V I think. Link to comment Share on other sites More sharing options...
Diff Posted March 28, 2011 Author Share Posted March 28, 2011 Thanks for the advice, I cleaned the terminals on the engine to chassis strap - this did not make any difference. Although the strap fixed to the top of the forward engine mount did not look like the best place to effect an earth - not exactly in direct contact with the chassis. Alternator is fine, I get 14v when running. Bob, I did check the voltage across the battery terminals. Sound if the voltage is dropping to 7v it will not start regardless cranking speed. I am away with work at the moment - will try with a fully charged battery (on a 4amp charger) when I get back later in the week. Matt, I will also check the spark plug leads Thanks for the suggestion guys. Link to comment Share on other sites More sharing options...
CageyH Posted March 28, 2011 Share Posted March 28, 2011 Check the small cable going to the solenoid on the starter - the one that passes right next to the exhaust manifold. My bet is on this being fried, taking a huge current to operate the solenoid. I have replaced mine, and run it round the back of the starter. Link to comment Share on other sites More sharing options...
Diff Posted March 29, 2011 Author Share Posted March 29, 2011 Hi guys, Well with a full charged battery and tight battery terminals the car just started.... once. The engine is cranking very slowly most if the time, but occasionally speeds up?!? Voltage fluctuates arround 6.8v and 8 volts?!? CageyH, the control wire to the solenoid is new. Any suggestions greatly received. Ian Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted March 30, 2011 Share Posted March 30, 2011 Send the battery back. Sounds like a duffer. Link to comment Share on other sites More sharing options...
Diff Posted March 31, 2011 Author Share Posted March 31, 2011 I think I have solved it..... I re did the spark plug leads checking they were connected properly and cutting down the foam packing. Bingo - started first time. BIG thanks to all who have replied and especially Matt Link to comment Share on other sites More sharing options...
Bob_Rich Posted March 31, 2011 Share Posted March 31, 2011 Hi glad U fixed it OK. Just one question that may help in the future How did U measure the battery voltage ? was it a Digital Voltmeter DVM ? If so it may be the voltage reading is in error because DVMs can be very inaccurate if the voltage varies during measurement. When cranking I would expect the voltage to dip at the peak of each compression stroke by at least 2V this could confuse a DVM reading anyway glad it fixed hope this helps. best of luck Bob Link to comment Share on other sites More sharing options...
Diff Posted April 2, 2011 Author Share Posted April 2, 2011 Still not starting properly. The rate of cranking is very unreliable. Almost let me down at the petrol station. How do you know if the starter motor is tired, I have changed everything else? Ian Link to comment Share on other sites More sharing options...
P150NR Posted April 3, 2011 Share Posted April 3, 2011 I've recently had the same problem and it was the starter motor - second one in four years. Link to comment Share on other sites More sharing options...
Diff Posted April 3, 2011 Author Share Posted April 3, 2011 Hi P150 What type did you get, I am thinking of going Brise? Ian Link to comment Share on other sites More sharing options...
P150NR Posted April 3, 2011 Share Posted April 3, 2011 I'm waiting for it to arrive from Caterham parts - so not sure till it turns up! Link to comment Share on other sites More sharing options...
Diff Posted April 22, 2011 Author Share Posted April 22, 2011 Update - I bit the bullet and ordered a Brise starter motor; Wow what a difference 😬 - the old motor aways sounded as though it was at its limits - the Brise turns the engine over with ease and sounds really smooth! Hopefully my starting woes are now a thing of the past. Ian Link to comment Share on other sites More sharing options...
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